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SCIENCE    PROGRESS 


ABERDEEN    UNIVERSITY    PRESS. 


Science 

rogre 


A  MONTHLY  REVIEW 


-*,•■. 


OF 


CURRENT  SCIENTIFIC  INVESTIGATION  \    ', 


A 


CONDUCTED    BY 

HENRY  C.  BURDETT 

EDITED    BY 

J.  BRETLAND  FARMER,  M.A. 


VOL.  V. 


THE   SCIENTIFIC   PRESS,   LIMITED,   428   Strand,   W.C. 


NEW  YORK,  BOSTON,  AND  CHICAGO  (SPECIAL 
AMERICAN  EDITION)  \  MESSRS.  D.  C.  HEATH 
AND    CO. 

DUBLIN  :  MESSRS.  FANNIN  AND  CO.,41  GRAFTON 
STREET 

EDINBURGH  :    MESSRS.  OLIVER  AND  BOYD 

GLASGOW:     MESSRS.    JOHN    MENZIES    AND    CO. 

TORONTO  I  THE  TORONTO  NEWS  CO. 

MONTREAL:  THE  MONTREAL  NEWS  CO. 


BERLIN  :  MESSRS.  A.  ASHER  AND  CO. 

PARIS:  LIBRAIRIE  GALIGNANI,  224  RUE  RIVOLI 

INDIA  :    MESSRS.  THACKER  AND  CO. 

MELBOURNE,  SYDNEY,  ~l  MESSRS.  GORDON 

ADELAIDE,  NEW  ZEALAND  :  J  AND  GOTCH 
SOUTH  AFRICA  :  MESSRS.  JUTA,  CAPE  TOWN 
LEIPZIG  :    MR.  A.  LORENTZ 


I896 

All  rights  reserved 


y?;< 


CONTENTS. 

GENERAL. 

PAGE 

African  Grass  Fires  and  their  Effects.     By  G.  F.  Scott  Elliott,  M.A.  77 

The  Past,  Present,  and  Future  Water  Supply  of  London.     By  E. 

Frankland,  F.R.S. 163 

Gold  Extraction  Processes.    By  T.  K.  Rose,  D.Sc,  Assistant  Assayer 

of  the  Royal  Mint     -------  484 

ANIMAL  MORPHOLOGY. 

The  Morphology  of  the  Mollusca.     By.  W.  Garstang,  M.A.,  Fellow 

of  Lincoln  College,  Oxford 38 

The  Present  Position  of  the  Cell  Theory,     By  G.  C.  Bourne,  M.A., 

Fellow  of  New  College,  Oxford  -         -         -94,227,304 

Some   Recent   Memoirs   upon    Oligochfeta.      By   F.   E.    Beddard, 

M.A.,  F.R.S. 19° 

ANTHROPOLOGY. 

Pre-historic  Man  in  the  Eastern  Mediterranean.     By  J.  L.  Myers, 

Fellow  of  Magdalen  College,  Oxford  -  -       335 

Selection  in  Man.     By  John  Beddoe,  M.D.,  LL.D.,  F.R.S.    -         -       384 

BOTANY. 

On  Recent  Advances  in  Vegetable  Cytology.  By  J.  Bretland  Farmer, 
M.A.,  Professor  of  Botany  in  the  Royal  College  of  Science, 
London  -  ---------22 

The  Reserve  Materials  of  Plants  [Concluded).  By  J.  Reynolds 
Green,  M.A.,  F.R.S.,  Professor  of  Botany  to  the  Pharma- 
ceutical Society,  London  ------         60 

The  Stelar  Theory :  A  History  and  a  Criticism.     By  A.  G.  Tansley, 

B.A. i33j  215 

Ferns  :  Aposporous  and  Apogamous.     By  C.  T.  Druery,  F.L.S.      -       242 

Insular  Floras.     By  W.  Botting  Hemsley,  F.R.S.-  -         -        286,374 

CHEMISTRY   AND  PHYSICS. 

The  General  Bearings  of  Magnetic  Observations.  By  Captain  Ettrick 
W.  Creak,  R.N.,  F.R.S.,  Superintendent  of  Compasses  to 
the  Admiralty  -         -         -         -         -         -         -         -         -         81 

Solid  Solutions.      By  James  Walker,   Ph.D.,   D.Sc,    Professor  of 

Chemistry  in  University  College,  Dundee   -         -         -         -       121 


2  /Sf& 


vi  CONTENTS. 


PAGE 


Notes  on  Atomic  Weights.     By  Alexander  Scott,  M.A.,  Jacksonian 

Demonstrator  in  the  University  of  Cambridge     -  202 

The  Growth  of  our  Knowledge  of  Helium.     By  J.  Norman  Lockyer, 

C.B.,  F.R.S.    ---------       249 

Light  and  Electrification.     By  Oliver  Lodge,  F.R.S.,  Professor  of 

Physics  in  University  College,  Liverpool     -         -         -         -       417 

Recent  Values  of  the  Magnetic  Elements  at  the  Principal  Magnetic 
Observatories  of  the  World.  By  Charles  Chree,  M.A., 
Superintendent  of  Kew  Observatory  -         -         -         -         -       499 


T 


GEOLOGY,   MINERALOGY  AND   PALAEONTOLOGY 

The  Graptolites.     By  J.  E.  Marr,  M.A.,  F.R.S.,  Fellow  of  St.  John's 

College,  Cambridge  --------       360 

Recent  Discoveries  in  Avian  Palaeontology.  By  C.  W.  Andrews  -  398 
An   Extinct  Plant  of  Doubtful  Affinity.     By  A.  C.  Seward,  M.A., 

F.G.S.,  University  Lecturer  in  Botany,  Cambridge  -       428 

The  Work  of  the  Portuguese  Geological  Survey.     By  Philip  Lake, 

M. A.,  St.  John's  College,  Cambridge-         -  439 

Petrology  in  America.     By  Alfred  Harker,  M.  A.,  Fellow  of  St.  John's 

College,  Cambridge-         -------       459 

PATHOLOGY. 

The  Hereditary  Transmission  of  Micro-organisms.     By  G.  A.  Buck- 
master,  M.D.,  Lecturer  on  Physiology  at  St.  George's  Hospital, 

London   ----------       324 

PHYSIOLOGY. 

Ludwig  and  Modern  Physiology.  By  J.  Burdon  Sanderson,  M.D., 
F.R.S.,  Regius  Professor  of  Physiology  in  the  University  of 
Oxford    ----------  1 

On  Some  Applications  of  the  Theory  of  Osmotic  Pressures  to 
Physiological  Problems  (Part  II.).  By  E.  H.  Starling,  M.D., 
Lecturer  on  Physiology  at  Guy's  Hospital,  London      -         -       151 

Iodine  in   the  Animal   Organism.      By  W.  D.   Halliburton,  M.D., 

F.R.S.,  Professor  of  Physiology  in  King's  College,  London  -       454 

APPENDIX  I. 
Notices  of  Books,        -         -         -         -         -         -       1,  xi,  xxi,  xxxi,  xli 

APPENDIX  II. 
Titles  of  Chemical  Papers,  -  iv,  xv,  xxv,  xxxm,  xlii,  xlvii 


ALPHABETICAL  LIST  OF  AUTHORS. 


PAGE 


Andrews,  C  W.     Recent  Discoveries  in  Avian  Palaeontology          -  398 

Beddard,  F.  E.     Some  Recent  Memoirs  upon  Oligochaeta      -  190 

Beddoe,  John.     Selection  in  Man                   -  384 

Bourne,  G.  C.     The  Present  Position  of  the  Cell  Theory         94,  227,  304 
Buckmaster,    G.    A.       The    Hereditary    Transmission    of     Micro- 
organisms        -                   -         -         -         -         -         -         ~324 

Chree,  Charles.     Recent  Values  of  the  Magnetic  Elements     -         -  499 
Creak,  Captain  Ettrick.    The  General  Bearings  of  Magnetic  Observa- 
tions                 ___-__---  81 
Druery,  C.  T.     Ferns :  Aposporous  and  Apogamous                 -         -  242 
Farmer,  J.  B.     On  Recent  Advances  in  Vegetable  Cytology  -         -  22 
Frankland,    E.     The  Past,  Present  and    Future  Water  Supply  of 

London      -------  163 

Garstang,  W.     The  Morphology  of  the  Mollusca    -  38 

Green,  J.  Reynolds.     The  Reserve  Materials  of  Plants    -  60 

Halliburton,  W.  D.     Iodine  in  the  Animal  Organism      -  454 

Harker,  Alfred.     Petrology  in  America          -         -  459 
Hemsley,  W.  Botting.    Insular  Floras    -         -         -                          286,  374 

Lake,  Philip.     The  Work  of  the  Portuguese  Geological  Survey  439 

Lockyer,  J.  Norman.    The  Growth  of  our  Knowledge  of  Helium      -  249 

Lodge,  Oliver.     Light  and  Electrification      -         -         -         -         -  417 

Marr,  J.  E.     The  Graptolites        ------  360 

Myers,  J.  L.     Prehistoric  Man  in  the  Eastern  Mediterranean           -  335 

Rose,  T.  R.     Gold  Extraction  Processes       -----  484 

Sanderson,  J.  Burdon.      Ludwig  and  Modern  Physiology         -          -  1 

Scott,  Alexander.     Notes  on  Atomic  Weights         ...         -  202 

Scott-Elliott,  G.  F.     African  Grass  Fires  and  their  Effects      -         -  77 

Seward,  A.  C.     An  Extinct  Plant  of  Doubtful  Affinity   -  428 
Starling,  E.  H.     On  some  Applications  of  the  Theory  of  Osmotic 

Pressures  to  Physiological  Problems   -         -         -         -         -  151 

Tansley,  A.  G.     The  Stellar  Theory     -  133,215 

Walker,  James.     Solid  Solutions  -         -         -         -         -         -         -  121 


l-\\ 


Btimce  progress 


ku  UlRARYbj 

-     ^7- 

a.      '    CV 


; 


No.  25. 


March,   1896. 


Vol.  V. 


LUDWIG  AND  MODERN  PHYSIOLOGY.1 

I.  INTRODUCTION. 

THE  death  of  any  discoverer — of  any  one  who  has 
added  largely  to  the  sum  of  human  knowledge — 
affords  a  reason  for  inquiring  what  his  work  was  and  how 
he  accomplished  it.  This  inquiry  has  interest  even  when 
the  work  has  been  completed  in  a  few  years  and  has  been 
limited  to  a  single  line  of  investigation — much  more  when 
the  life  has  been  associated  with  the  origin  and  develop- 
ment of  a  new  science  and  has  extended  over  half  a 
century. 

The  Science  of  Physiology  as  we  know  it  came  into 
existence  fifty  years  ago  with  the  beginning  of  the  active  life 
of  Ludwig,  in  the  same  sense  that  the  other  great  branch  of 
Biology,  the  Science  of  Living  Beings  (Ontology),  as  we 
now  know  it,  came  into  existence  with  the  appearance  of  the 
"  Origin  of  Species  ".  In  the  order  of  time  Physiology  had 
the  advantage,  for  the  new  Physiology  was  accepted  some 
ten  years  before  the  Darwinian  epoch.  Notwithstanding,  the 
content  of  the  science  is  relatively  so  unfamiliar,  that  before 
entering:  on  the  discussion  of  the  life  and  work  of  the  man 
who,  as  I  shall  endeavour  to  show,  had  a  larger  share  in 
founding  it  than  any  of  his  contemporaries,  it  is  necessary 
to  define  its  limits  and  its  relations  to  other  branches  of 
knowledge. 

1  Founded   upon  a  lecture  delivered   at   the   Royal  Institution,    Jan. 
24,   1896. 


2  SCIENCE  PROGRESS. 

The  word  Physiology  has  in  modern  times  changed  its 
meaning.  It  once  comprehended  the  whole  knowledge  of 
Nature.  Now  it  is  the  name  for  one  of  the  two  Divisions 
of  the  Science  of  Life.  In  the  progress  of  investigation 
the  study  of  that  Science  has  inevitably  divided  itself  into 
two  :  Ontology,  the  Science  of  Living  Beings  ;  Physiology, 
the  Science  of  Living  Processes,  and  thus,  inasmuch  as 
Life  consist  in  processes,  of  Life  itself.  Both  strive  to 
understand  the  complicated  relations  and  endless  varieties 
which  present  themselves  in  living  Nature,  but  by  different 
methods.  Both  refer  to  general  principles,  but  they  are  of 
a  different  nature. 

To  the  Ontologist,  the  student  of  Living  Beings,  Plants 
or  Animals,  the  great  fact  of  Evolution,  namely,  that  from 
the  simplest  beginning  our  own  organism,  no  less  than  that 
of  every  animal  and  plant  with  its  infinite  complication  of 
parts  and  powers,  unfolds  the  plan  of  its  existence — taken 
with  the  observation  that  that  small  beginning  was,  in  all 
excepting  the  lowest  forms,  itself  derived  from  two  parents, 
equally  from  each — is  the  basis  from  which  his  study  and 
knowledge  of  the  world  of  living  beings  takes  its  departure. 
For  on  these  two  facts — Evolution  and  Descent — the  ex- 
plorer of  the  forms,  distribution  and  habits  of  animals  and 
plants  has,  since  the  Darwinian  epoch,  relied  with  an  ever- 
increasing  certainty,  and  has  found  in  them  the  explanation 
of  every  phenomenon,  the  solution  of  every  problem  relating 
to  the  subject  of  his  inquiry.  Nor  could  he  wish  for  a  more 
secure  basis.  Whatever  doubts  or  misgivings  exist  in  the 
minds  of  "  non-biologists  "  in  relation  to  it,  may  be  attributed 
partly  to  the  association  with  the  doctrine  of  Evolution  of 
questions  which  the  true  naturalist  regards  as  transcen- 
dental ;  partly  to  the  perversion  or  weakening  of  meaning 
which  the  term  has  suffered  in  consequence  of  its  introduc- 
tion into  the  language  of  common  life,  and  particularly  to 
the  habit  of  applying  it  to  any  kind  of  progress  or  improve- 
ment, anything  which  from  small  beginnings  gradually 
increases.  But,  provided  that  we  limit  the  term  to  its 
original  sense — the  Evolution  of  a  living  being  from  its 
germ  by  a  continuous,   not  a  gradual  process — there  is  no 


LUDWIG  AND  MODERN  PHYSIOLOGY.  3 

conception  which  is  more  free  from  doubt  either  as  to  its 
meaning  or  reality.  It  is  inseparable  from  that  of  Life 
itself,  which  is  but  the  unfolding  of  a  predestined  harmony, 
of  a  prearranged  consensus  and  synergy  of  parts. 

The  other  branch  of  Biology,  that  with  which  Ludwig's 
name  is  associated,  deals  with  the  same  facts  in  a  different 
way.  While  Ontology  regards  animals  and  plants  as  in- 
dividuals and  in  relation  to  other  individuals,  Physiology 
considers  the  processes  themselves  of  which  life  is  a  complex. 
This  is  the  most  obvious  distinction,  but  it  is  subordinate  to 
the  fundamental  one,  namely,  that  while  Ontology  has  for 
its  basis  laws  which  are  in  force  only  in  its  own  province, 
those  of  Evolution,  Descent,  and  Adaptation,  we  Physiolo- 
gists, while  accepting  these  as  true,  found  nothing  upon  them, 
using  them  only  for  euristic  purposes,  i.e.,  as  guides  to  dis- 
covery, not  for  the  purpose  of  explanation.  Purposive  Adapta- 
tion, for  example,  serves  as  a  clue,  by  which  we  are  constantly 
guided  in  our  exploration  of  the  tangled  labyrinth  of  vital 
processes.  But  when  it  becomes  our  business  to  explain 
these  processes — to  say  how  they  are  brought  about — we 
refer  them  not  to  biological  principles  of  any  kind,  but  to 
the  Universal  Laws  of  Nature.  Hence  it  happens  that 
with  reference  to  each  of  these  processes,  our  inquiry  is 
rather  how  it  occurs  than  why  it  occurs. 

It  has  been  well  said  that  the  Natural  Sciences  are  the 
children  of  necessity.  Just  as  the  other  Natural  Sciences 
owed  their  origin  to  the  necessity  of  acquiring  that  control 
over  the  forces  of  Nature  without  which  life  would 
scarcely  be  worth  living,  so  Physiology  arose  out  of  human 
suffering  and  the  necessity  of  relieving  it.  It  sprang  indeed 
out  of  Pathology.  It  was  suffering  that  led  us  to  know,  as 
regards  our  own  bodies,  that  we  had  internal  as  well  as 
external  organs,  and  probably  one  of  the  first  generalisa- 
tions which  arose  out  of  this  knowledge  was,  that  "  if  one 
member  suffer  all  the  members  suffer  with  it  " — that  all 
work  together  for  the  good  of  the  whole.  In  earlier  times 
the  good  which  was  thus  indicated  was  associated  in  men's 
minds  with  human  welfare  exclusively.  But  it  was 
eventually  seen  that  Nature  has  no  less  consideration  for 


4  SCIENCE  PROGRESS. 

the  welfare  of  those  of  her  products  which  to  us  seem 
hideous  or  mischievous,  than  for  those  which  we  regard 
as  most  useful  to  man  or  most  deserving  of  his  admiration. 
It  thus  became  apparent  that  the  good  in  question  could  not 
be  human  exclusively,  but  as  regards  each  animal  its  oivn 
good — and  that  in  the  organised  world  the  existence  and 
life  of  every  species  is  brought  into  subordination  to  one 
purpose — its  own  success  in  the  struggle  for  existence.1 

From  what  has  preceded  it  may  be  readily  understood 
that  in  Physiology,  Adaptation  takes  a  more  prominent 
place  than  Evolution  or  Descent.  In  the  prescientific 
period  adaptation  was  everything.  The  observation  that 
any  structure  or  arrangement  exhibited  marks  of  adaptation 
to  a  useful  purpose  was  accepted  not  merely  as  a  guide  in 
research,  but  as  a  full  and  final  explanation.  Of  an  organism 
or  organ  which  perfectly  fulfilled,  in  its  structure  and  work- 
ing, the  end  of  its  existence,  nothing  further  required  to  be 
said  or  known.  Physiologists  of  the  present  day  recognise 
as  fully  as  their  predecessors  that  perfection  of  contrivance 
which  displays  itself  in  all  living  structures,  the  more  ex- 
quisitely the  more  minutely  they  are  examined.  No  one, 
for  example,  has  written  more  emphatically  on  this  point 
than  did  Ludwig.  In  one  of  his  discourses,  after  showing 
how  Nature  exceeds  the  highest  standard  of  human  attain- 
ment — how  she  fashions  as  it  were  out  of  nothing  and  with- 
out tools,  instruments  of  a  perfection  which  the  human 
artificer  cannot  reach,  though  provided  with  every  suitable 
material — wood,  brass,  glass,  india-rubber — he  gives  the 
organ   of  sight   as  a    signal   example,   referring  among  its 

1 1  am  aware  that  in  thus  stating  the  relation  between  adaptation  and  the 
struggle  for  existence,  I  may  seem  to  be  reversing  the  order  followed  by 
Mr.  Darwin,  inasmuch  as  he  regarded  the  survival  of  organisms  which  are 
fittest  for  their  place  in  Nature,  and  of  parts  which  are  fittest  for  their 
place  in  the  organism,  as  the  agency  by  which  adaptedness  is  brought  about. 
However  this  may  be  expressed  it  cannot  be  doubted  that  fitness  is  an 
essential  of  organisms.  Living  beings  are  the  only  things  in  Nature  which 
by  virtue  of  evolution  and  descent  are  able  to  adapt  themselves  to  their 
surroundings.  It  is  therefore  only  so  far  as  organism  (with  all  its  attri- 
butes) is  presupposed,  that  the  dependence  of  adaptation  on  survival  is 
intelligible. 


LUDWIG  AND  MODERN  PHYSIOLOGY.  5 

other  perfections  to  the  rapidity  with  which  the  eye  can 
be  fixed  on  numerous  objects  in  succession  and  the  instan- 
taneous and  unconscious  estimates  which  we  are  able  to 
form  of  the  distances  of  objects,  each  estimate  involving  a 
process  of  arithmetic  which  no  calculating  machine  could 
effect  in  the  time.1  In  another  discourse — that  given  at 
Leipzig  when  he  entered  on  his  professorship  in  1865 — he  re- 
marks that  when  in  our  researches  into  the  finer  mechanism 
of  an  organ  we  at  last  come  to  understand  it,  we  are 
humbled  by  the  recognition  "  that  the  human  inventor  is 
but  a  blunderer  as  compared  with  the  unknown  Master  of 
the  animal  creation  ",2 

Some  readers  will  perhaps  remember  how  one  of  the 
most  brilliant  of  philosophical  writers,  in  a  discourse  to  the 
British  Association  delivered  a  quarter  of  a  century  ago, 
averred  on  the  authority  of  a  great  Physiologist  that  the 
eye,  regarded  as  an  optical  instrument,  was  so  inferior  a 
production  that  if  it  were  the  work  of  a  mechanician  it 
would  be  unsaleable.  Without  criticising  or  endeavouring 
to  explain  this  paradox,  I  may  refer  to  it  as  having  given 
the  countenance  of  a  distinguished  name  to  a  misconception 
which  I  know  exists  in  the  minds  of  many  persons,  to  the 
effect  that  the  scientific  Physiologist  is  more  or  less  blind  to 
the  evidence  of  design  in  creation.  On  the  contrary,  the 
view  taken  by  Ludwig,  as  expressed  in  the  words  I  have 
quoted,  is  that  of  all  Physiologists.  The  disuse  of  the 
teleological  expressions  which  were  formerly  current  does 
not  imply  that  the  indications  of  contrivance  are  less  ap- 
preciated, for,  on  the  contrary,  we  regard  them  as  more 
characteristic  of  organism  as  it  presents  itself  to  our  obser- 
vation than  any  other  of  its  endowments.      But,  if  I   may 

1  I  summarise  here  from  a  very  interesting  lecture  entitled  "  Leid  und 
Freude  in  der  Naturforschung  "  published  in  the  Gartenlaube  (Nos.  22  and 
23)  in   1870. 

2  The  words  translated  in  the  above  sentence  are  as  follows  :  "  Wenn 
uns  endlich  die  Palme  gereicht  wird,  wenn  wir  ein  Organ  in  seinem 
Zuzammenhang  begreifen,  so  wird  unser  stolzes  Gattungsbewusstsein  durch 
die  Erkenntniss  niedergedruckt,  dass  der  menschlicher  Erfinder  ein  Stumper 
gegen  den  unbekannten  Meister  der  thierischen  Schbpfung  sei  ". 


6  SCIENCE  PROGRESS. 

be  permitted  to  repeat  what  has  been  already  said,  we  use 
the  evidences  of  adaptation  differently.  We  found  no  ex- 
planation on  this  or  any  other  biological  principle,  but  refer 
all  the  phenomena  by  which  these  manifest  themselves  to 
the  simpler  and  more  certain  Physical  Laws  of  the  Universe. 

Why  must  we  take  this  position  ?  First,  because  it  is  a 
general  rule  in  investigations  of  all  kinds  to  explain  the 
more  complex  by  the  more  simple.  The  material  Universe 
is  manifestly  divided  into  two  parts,  the  living  and  the  non- 
living. We  may,  if  we  like,  take  the  living  as  our  Norma, 
and  say  to  the  Physicists,  You  must  come  to  us  for  Laws, 
you  must  account  for  the  play  of  energies  in  universal  nature 
by  referring  them  to  Evolution,  Descent,  Adaptation.  Or 
we  may  take  these  words  as  true  expressions  of  the  mutual 
relations  between  the  phenomena  and  processes  peculiar  to 
living  beings,  using  for  the  explanation  of  the  processes 
themselves  the  same  methods  which  we  should  employ  if 
we  were  engaged  in  the  investigation  of  analogous  pro- 
cesses going  on  independently  of  life.  Between  these  two 
courses  there  seems  to  me  to  be  no  third  alternative,  unless 
we  suppose  that  there  are  two  material  Universes,  one  to 
which  the  material  of  our  bodies  belongs,  the  other  com- 
prising everything  that  is  not  either  plant  or  animal. 

The  second  reason  is  a  practical  one.  We  should  have 
to  go  back  to  the  time  which  I  have  ventured  to  call  pre- 
scientific,  when  the  world  of  life  and  organisation  was  sup- 
posed to  be  governed  exclusively  by  its  own  Laws.  The 
work  of  the  past  fifty  years  has  been  done  on  the  opposite 
principle,  and  has  brought  light  and  clearness  where  there 
was  before  obscurity  and  confusion.  All  this  progress  we 
should  have  to  repudiate,  but  this  would  not  be  all.  We 
should  have  to  forego  the  prospect  of  future  advance. 
Whereas  by  holding  on  our  present  course,  gradually  pro- 
ceeding from  the  more  simple  to  the  more  complex,  from 
the  physical  to  the  vital,  we  may  confidently  look  forward 
to  extending  our  knowledge  considerably  beyond  its  present 
limits. 

A  no  less  brilliant  writer  than  the  one  already  referred 
to,  who  is  also  no  longer  with  us,  asserted  that  mind  was  a 


LUDWIG  AND  MODERN  PHYSIOLOGY.  y 

secretion  of  the  brain  in  the  same  sense  that  bile  is  a  secretion 
of  the  liver  or  urine  that  of  the  kidney  ;  and  many  people 
have  imagined  this  to  be  the  necessary  outcome  of  a  too 
mechanical  way  of  looking  at  vital  phenomena,  and  that 
Physiologists,  by  a  habit  of  adhering  strictly  to  their  own 
method,  have  failed  to  see  that  the  organism  presents  prob- 
lems to  which  this  method  is  not  applicable,  such,  e.g.,  as 
the  origin  of  the  organism  itself,  or  the  origin  and  develop- 
ment in  it  of  the  mental  faculty.  The  answer  to  this  sug- 
gestion is  that  these  questions  are  approached  by  Physio- 
logists only  in  so  far  as  they  are  approachable.  We  are 
well  aware  that  our  business  is  with  the  unknown  knowable, 
not  with  the  transcendental.  During  the  last  twenty  years 
there  has  been  a  considerable  forward  movement  in  Physio- 
logy in  the  psychological  direction,  partly  dependent  on 
discoveries  as  to  the  localisation  of  the  higher  functions  of 
the  nervous  system,  partly  on  the  application  of  methods  of 
measurement  to  the  concomitant  phenomena  of  psychical 
processes.  And  these  researches  have  brought  us  to  the 
very  edge  of  a  region  which  cannot  be  explored  by  our 
methods — where  measurements  of  time  or  of  space  are  no 
longer  possible. 

In  approaching  this  limit  the  Physiologist  is  liable  to  fall 
into  two  mistakes — on  the  one  hand,  that  of  passing  into 
the  transcendental  without  knowing  it  ;  on  the  other,  that 
of  assuming  that  what  he  does  not  know  is  not  knowledge. 
The  first  of  these  risks  seems  to  me  of  little  moment ;  first, 
because  the  limits  of  natural  knowledge  in  the  psychological 
direction  have  been  well  defined  by  the  best  writers,  as,  e.g., 
by  du  Bois-Reymond  in  his  well-known  essay  "On  the 
Limits  of  Natural  Knowledge,"  but  chiefly  because  the  in- 
vestigator who  knows  what  he  is  about  is  arrested  in  limine 
by  the  impossibility  of  applying  the  experimental  method 
to  questions  beyond  its  scope.  The  other  mistake  is  chiefly 
fallen  into  by  careless  thinkers,  who,  while  they  object  to 
the  employment  of  intuition  even  in  regions  where  intuition 
is  the  only  method  by  which  anything  can  be  learned, 
attempt  to  describe  and  define  mental  processes  in  mechan- 
ical terms,  assigning  to  these  terms  meanings  which  science 


8  SCIENCE  PROGRESS. 

does  not  recognise,  and  thus  slide  into  a  kind  of  speculation 
which  is  as  futile  as  it  is  unphilosophical. 

II.    LUDWIG  AS  INVESTIGATOR  AND  TEACHER. 

The  uneventful  history  of  Ludwig's  life — how  early  he 
began  his  investigation  of  the  anatomy  and  function  of  the 
kidneys  ;  how  he  became  just  fifty  years  ago  titular  Pro- 
fessor at  Marburg,  in  the  small  University  of  his  native 
State,  Hesse  Cassel  ;  how  in  1849  he  removed  to  Zurich  as 
actual  Professor  and  thereupon  married  ;  how  he  was  six 
years  later  promoted  to  Vienna — has  already  been  admirably 
related  in  these  pages  by  Dr.  Stirling.  In  1865,  after 
twenty  years  of  professorial  experience,  but  still  in  the 
prime  of  life  and,  as  it  turned  out,  with  thirty  years  of 
activity  still  before  him,  he  accepted  the  Chair  of  Physio- 
logy at  Leipzig.  His  invitation  to  that  great  University 
was  by  far  the  most  important  occurrence  in  his  life,  for  the 
liberality  of  the  Saxon  Government,  and  particularly  the 
energetic  support  which  he  received  from  the  enlightened 
Minister  v.  Falkenstein,  enabled  him  to  accomplish  for 
Physiology  what  had  never  before  been  attempted  on  an 
adequate  scale.  No  sooner  had  he  been  appointed  than 
he  set  himself  to  create  what  was  essential  to  the 
progress  of  the  Science — a  great  Observatory,  arranged 
not  as  a  Museum,  but  much  more  like  a  physical  and 
chemical  Laboratory,  provided  with  all  that  was  needed  for 
the  application  of  exact  methods  of  research  to  the  investiga- 
tion of  the  processes  of  Life.  The  idea  which  he  had  ever  in 
view,  and  which  he  carried  into  effect  during  the  last  thirty 
years  of  his  life  with  signal  success,  was  to  unite  his  life- 
work  as  an  investigator  with  the  highest  kind  of  teaching. 
Even  at  Marburg  and  at  Zurich  he  had  begun  to  form  a 
School ;  for  already  men  nearly  of  his  own  age  had  rallied 
round  him.  Attracted  in  the  first  instance  by  his  early 
discoveries,  they  were  held  by  the  force  of  his  character, 
and  became  permanently  associated  with  him  in  his  work 
as  his  loyal  friends  and  followers — in  the  highest  sense  his 
scholars.      If,  therefore,  we  speak  of  Ludwig  as  one  of  the 


LUDWIG  AND  MODERN  PHYSIOLOGY.  o, 

greatest  teachers  of  Science  the  world  has  seen,  we 
have  in  mind  his  relation  to  the  men  who  ranged  them- 
selves under  his  leadership  in  the  building  up  of  the  Science 
of  Physiology,  without  reference  to  his  function  as  an 
ordinary  academical  teacher. 

Of  this  relation  we  can  best  judge  by  the  careful  perusal 
of  the  numerous  biographical  memoirs  which  have  appeared 
since  his  death,  more  particularly  those  of  Professor  His1 
(Leipzig),  of  Professor  Kronecker2  (Bern),  who  was  for 
many  years  his  coadjutor  in  the  Institute,  of  Professor  v. 
Fick  3  (Wlirzburg),  of  Professor  v.  Kries  *  (Freiburg),  of 
Professor  Mosso5  (Turin),  of  Professor  Fano  6  (Florence), 
of  Professor  Tigerstedt 7  (Upsala),  of  Professor  Stirling  s 
in  England.  With  the  exception  of  Fick,  whose  relations  with 
Ludwig  were  of  an  earlier  date,  and  of  his  colleague  in  the 
Chair  of  Anatomy,  all  of  these  distinguished  teachers  were 
at  one  time  workers  in  the  Leipzig  Institute.  All  testify 
their  love  and  veneration  for  the  master,  and  each  contributes 
some  striking  touches  to  the  picture  of  his  character. 

All  Ludwig's  investigations  were  carried  out  with  his 
scholars.  He  possessed  a  wonderful  faculty  of  setting  each 
man  to  work  at  a  problem  suited  to  his  talent  and  previous 
training,  and  this  he  carried  into  effect  by  associating  him 
with  himself  in  some  research  which  he  had  either  in 
progress  or  in  view.  During  the  early  years  of  the  Leip- 
zig period,  all  the  work  done  under  his  direction  was 
published  in  the  well-known  volumes  of  the  Arbeiten,  and 

1  His.  "  Karl  Ludwig  und  Karl  Thiersch.''  Akademische  Geddcht- 
nissrede,  Leipzig,  1S95. 

2  Kronecker.      "Carl  Friedrich   Wilhelm    Ludwig."     Berliner  Klin, 
Wochensch.,  1895,  No.  21. 

3  A.  Fick.  "  Karl  Ludwig."  Nachruf.  Biographische  Blatter,  Berlin, 
vol.  i.,  pt.  3. 

4  v.  Kries.     "Carl  Ludwig."     Freiburg,  Bd.  i.,  1895. 

5  Mosso.     "  Karl  Ludwig."     Die  Nation,  Berlin,  Nos.  38,  39. 

6  Fano.  "  Per  Carlo  Ludwig  Commemorazione."  Clinica  Afodema, 
Florence,  i.,  No.  7. 

7  Tigerstedt.  "  Karl  Ludwig."  Denkrede.  Biographische  Blatter,  Berlin, 
vol.  i.,  pt.  3. 

8  Stirling.     "Science  Progress,"  vol.  iv.,  No.  21. 


io  SCIENCE  PROGRESS. 

subsequently  in  the  Archiv  fur  Anat.  unci  Physiologic  of 
du  Bois-Reymoncl.  Each  "  Arbeit  ':  of  the  laboratory 
appeared  in  print  under  the  name  of  the  scholar  who 
operated  with  his  master  in  its  production,  but  the 
scholar's  part  in  the  work  done  varied  according  to  its 
nature  and  his  ability.  Sometimes,  as  v.  Kries  says,  he  sat 
on  the  window-sill  while  Ludwig  with  the  efficient  help  of 
his  laboratory  assistant  Salvenmoser,  did  the  whole  of  the 
work.  In  all  cases  Ludwig  not  only  formulated  the 
problem,  but  indicated  the  course  to  be  followed  in  each 
step  of  the  investigation,  calling  the  worker,  of  course,  into 
counsel.  In  the  final  working  up  of  the  results  he  always 
took  a  principal  part,  and  often  wrote  the  whole  paper.  But 
whether  he  did  little  or  much,  he  handed  over  the  whole 
credit  of  the  performance  to  his  coadjutor.  This  method  of 
publication  has  no  doubt  the  disadvantage  that  it  leaves 
it  uncertain  what  part  each  had  taken  ;  but  it  is  to  be 
remembered  that  this  drawback  is  unavoidable  whenever 
master  and  scholar  work  together,  and  is  outweighed  by  the 
many  advantages  which  arise  from  this  mode  of  co-opera- 
tion. The  instances  in  which  any  uncertainty  can  exist  in 
relation  to  the  real  authorship  of  the  Leipzig  work  are 
exceptional.  The  well-informed  reader  does  not  need  to 
be  told  that  Mosso  or  Schmidt,  Brunton  or  Gaskell,  Stirling 
or  Wooldridge  were  the  authors  of  their  papers  in  a  sense 
very  different  from  that  in  which  the  term  could  be  applied 
to  some  others  of  Ludwig's  pupils.  On  the  whole  the  plan 
must  be  judged  of  by  the  results.  It  was  by  working  with 
his  scholars  that  Ludwig  trained  them  to  work  afterwards  by 
themselves  ;  and  thereby  accomplished  so  much  more  than 
other  great  teachers  have  done. 

I  do  not  think  that  any  of  Ludwig's  contemporaries 
could  be  compared  to  him  in  respect  of  the  wide  range  of 
his  researches.  In  a  science  distinguished  from  others  by 
the  variety  of  its  aims,  he  was  equally  at  home  in  all 
branches,  and  was  equally  master  of  all  methods,  for  he 
recognised  that  the  most  profound  biological  question  can 
only  be  solved  by  combining  anatomical,  physical  and 
and  chemical  inquiries.      It  was  this  consideration  which  led 


LUDWIG  AND  MODERN  PHYSIOLOGY.  n 

him  in  planning  the  Leipzig  Institute  to  divide  it  into  three 
parts,  experimental  (in  the  more  restricted  sense),  chemical 
and  histological.  Well  aware  that  it  was  impossible  for  a 
man  who  is  otherwise  occupied  to  maintain  his  familiarity 
with  the  technical  details  of  Histology  and  Physiological 
Chemistry,  he  placed  these  departments  under  the  charge 
of  younger  men  capable  of  keeping  them  up  to  the  rapidly 
advancing  standard  of  the  time,  his  relations  with  his 
coadjutors  being  such  that  he  had  no  difficulty  in  retaining 
his  hold  of  the  threads  of  the  investigation  to  which  these 
special  lines  of  inquiry  were  contributory. 

It  is  scarcely  necessary  to  say  that  as  an  experimenter 
Ludwig  was  unapproachable.  The  skill  with  which  he 
carried  out  difficult  and  complicated  operations,  the  care 
with  which  he  worked,  his  quickness  of  eye  and  certainty 
of  hand  were  qualities  which  he  had  in  common  with  great 
surgeons.  In  employing  animals  for  experiment  he  strongly 
objected  to  rough  and  ready  methods,  comparing  them  to 
"  firing  a  pistol  into  a  clock  to  see  how  it  works  ".  Every 
experiment  ought,  he  said,  to  be  carefully  planned  and 
meditated  on  beforehand,  so  as  to  accomplish  its  scientific 
purpose  and  avoid  the  infliction  of  pain.  To  ensure  this 
he  performed  all  operations  himself,  only  rarely  committing 
the  work  to  a  skilled  coadjutor. 

His  skill  in  anatomical  work  was  equally  remarkable. 
It  had  been  acquired  in  early  days,  and  appeared  throughout 
his  life  to  have  given  him  very  great  pleasure,  for  Mosso 
tells  how,  when  occupying  the  room  adjoining  that  in  which 
Ludwig  was  working  as  he  usually  did  by  himself,  he  heard 
the  outbursts  of  glee  which  accompanied  each  successful  step 
in  some  difficult  anatomical  investigation. 

Let  us  now  examine  more  fully  the  part  which  Ludwig 
played  in  the  revolution  of  ideas  as  to  the  nature  of  vital 
processes  which,  as  we  have  seen,  took  place  in  the  middle 
of  the  present  century. 

Although,  as  we  shall  see  afterwards,  there  were  many 
men  who,  before  Ludwig's  time,  investigated  the  phenomena 
of  life  from  the  physical  side,  it  was  he  and  the  contem- 
poraries who  were  associated   with   him    who   first   clearly 


12  SCIENCE  PROGRESS. 

recognised  the  importance  of  the  principle  that  vital  pheno- 
mena can  only  be  understood  by  comparison  with  their  physical 
counterparts,  and  foresaw  that  in  this  principle  the  future  of 
Physiology  was  contained  as  in  a  nutshell.  Feeling  strongly 
the  fruitlessness  and  unscientific  character  of  the  doctrines 
which  were  then  current,  they  were  eager  to  discover 
chemical  and  physical  relations  in  the  processes  of  life. 
In  Ludwig's  intellectual  character  this  eagerness  expressed 
his  dominant  motive.  Notwithstanding  that  his  own  re- 
searches had  in  many  instances  proved  that  there  are  im- 
portant functions  and  processes  in  the  animal  organism 
which  have  no  physical  or  chemical  analogues,  he  never 
swerved  either  from  the  principle  or  from  the  method 
founded  upon  it. 

Although  Ludwig  was  strongly  influenced  by  the  rapid 
progress  which   was  being  made   in   scientific   discovery  at 
the  time  that  he  entered  on  his  career,  he  derived  little  from 
his   immediate   predecessors   in   his    own    science.       He   is 
sometimes  placed  among  the  pupils  of  the  great  Comparative 
Anatomist  and  Physiologist,  J.  Mliller.     This,  however,  is  a 
manifest  mistake,  for  Ludwig  did  not  visit  Berlin  until  1847, 
when  Miiller  was  nearly  at  the  end  of  his  career.      At  that 
time   he   had   already  published   researches  of  the   highest 
value  (those  on  the  Mechanism  of  the  Circulation  and  on  the 
Physiology  of  the    Kidney),   and   had  set  forth  the  line  in 
which   he  intended  to  direct  his  investigations.      The  only 
earlier   Physiologist  with  whose  work  that  of  Ludwig  can 
be  said  to  be  in  real  continuity  was  E.  H.  Weber,  whom  he 
succeeded  at   Leipzig,  and  strikingly  resembled  in  his  way 
of  working.     For  Weber,  Ludwig  expressed  his  veneration 
more  unreservedly  than  for  any  other  man,  excepting  per- 
haps Helmholtz,  regarding  his  researches  as  the  foundation 
on  which  he  himself  desired  to  build.      Of  his  colleagues  at 
Marburg  he  was  indebted  in  the  first  place  to  the  anatomist, 
Professor  Ludwig  Fick,  in  whose  department  he  began  his 
career  as  Prosector,  and  to  whom  he  owed  facilities  without 
which  he  could  not  have  carried  out  his  earlier  researches  ; 
and  in  an  even  higher  degree  to  the  great  chemist,  R.  W. 
Bunsen,  from  whom  he  derived  that  training  in  the  exact 


LUDWIG  AND  MODERN  PHYSIOLOGY.  13 

sciences  which  was  to  be  of  such  inestimable  value  to  him 
afterwards. 

There  is  reason,  however,  to  believe  that,  as  so  often 
happens,  Ludwig's  scientific  progress  was  much  more  in- 
fluenced by  his  contemporaries  than  by  his  seniors.  In 
1847,  as  we  learn  on  the  one  hand  from  du  Bois-Reymond, 
on  the  other  from  Ludwig  himself,  he  visited  Berlin  for  the 
first  time.  This  visit  was  an  important  one  both  for  him- 
self and  for  the  future  of  Science,  for  he  there  met  three 
men  of  his  own  age,  Helmholtz,  du  Bois-Reymond  and 
Brticke,  who  were  destined  to  become  his  life-friends,  all  of 
whom  lived  nearly  as  long  as  Ludwig  himself,  and  attained 
to  the  highest  distinction.  They  all  were  full  of  the  same 
enthusiasm.  As  Ludwig  said  when  speaking  of  this  visit  : 
"  We  four  imagined  that  we  should  constitute  Physiology 
on  a  chemico-physical  foundation,  and  give  it  equal  scientific 
rank  with  Physics,  but  the  task  turned  out  to  be  much  more 
difficult  than  we  anticipated  ".  These  three  young  men, 
who  were  devoted  disciples  of  the  great  Anatomist,  had  the 
advantage  over  their  master  in  the  better  insight  which 
their  training  had  given  them  into  the  fundamental  prin- 
ciples of  scientific  research.  They  had  already  gathered 
around  themselves  a  so-called  "physical  "  school  of  Physio- 
logy, and  welcomed  Ludwig  on  his  arrival  from  Marburg 
as  one  who  had  of  his  own  initiative  undertaken  in  his  own 
University  das  Befremngswerk  aus  dcm  Vitalismus. 

The  determination  to  refer  all  vital  phenomena  to  their 
physical  or  chemical  counterparts  or  analogues,  which,  as  I 
have  said,  was  the  dominant  motive  in  Ludwio's  char- 
acter,  was  combined  with  another  quality  of  mind  which  if 
not  equally  influential  was  even  more  obviously  displayed  in 
his  mode  of  thinking  and  working.  His  first  aim,  even 
before  he  sought  for  any  explanation  of  a  structure  or  of 
a  process,  was  to  possess  himself,  by  all  means  of  observa- 
tion at  his  disposal,  of  a  complete  objective  conception  of 
all  its  relations.  He  regarded  the  faculty  of  vivid  sensual 
realisation  (lebendige  sinnliche  Anschanung)  as  of  special 
value  to  the  investigator  of  natural  phenomena,  and  did  his 
best  to  cultivate   it  in   those  who  worked  with  him   in   the 


14  SCIENCE  PROGRESS. 

laboratory.  In  himself,  this  objective  tendency  (if  I  may 
be  permitted  the  use  of  a  word  which,  if  not  correct,  seems 
to  express  what  I  mean)  might  be  regarded  as  almost  a 
defect,  for  it  made  him  indisposed  to  appreciate  any  sort  of 
knowledge  which  deals  with  the  abstract.  He  had  a 
disinclination  to  philosophical  speculation  which  almost 
amounted  to  aversion,  and,  perhaps  for  a  similar  reason, 
avoided  the  use  of  mathematical  methods  even  in  the 
discussion  of  scientific  questions  which  admitted  of  being 
treated  mathematically — contrasting  in  this  respect  with 
his  friend  du  Bois-Reymond,  resembling  Brlicke.  But 
as  a  teacher  the  quality  was  of  immense  use  to  him.  His 
power  of  vivid  realisation  was  the  substratum  of  that  many- 
sidedness  which  made  him,  irrespectively  of  his  scientific 
attainments,  so  attractive  a  personality. 

I  am  not  sure  that  it  can  be  generally  stated  that  a  keen 
scientific  observer  is  able  to  appreciate  the  artistic  aspects 
of  Nature.  In  Ludwig's  case,  however,  there  is  reason  to 
think  that  aesthetic  faculty  was  as  developed  as  the  power  of 
scientific  insight.  He  was  a  skilful  draughtsman  but  not 
a  musician  ;  both  arts  were,  however,  a  source  of  enjoy- 
ment to  him.  He  was  a  regular  frequenter  of  the  Gewand- 
kaus  concerts,  and  it  was  his  greatest  pleasure  to  bring  to- 
gether gifted  musicians  in  his  house,  where  he  played  the 
part  of  an  intelligent  and  appreciative  listener.  Of  painting 
he  knew  more  than  of  music,  and  was  a  connoisseur  whose 
opinion  carried  weight.  It  is  related  that  he  was  so  worried 
by  what  he  considered  bad  art,  that  after  the  redecoration 
of  the  Gczvandhaus  concert-room,  he  was  for  some  time 
deprived  of  his  accustomed  pleasure  in  listening  to  music. 

Ludwig's  social  characteristics  can  only  be  touched  on 
here  in  so  far  as  they  serve  to  make  intelligible  his  wonder- 
ful influence  as  a  teacher.  Many  of  his  pupils  at  Leipzig 
have  referred  to  the  schbne  Gemeinsamkeit  which  char- 
acterised the  life  there.  The  harmonious  relation  which, 
as  a  rule,  subsisted  between  men  of  different  education  and 
different  nationalities,  could  not  have  been  maintained  had 
not  Ludwig  possessed  side  by  side  with  that  inflexible 
earnestness   which   he   showed    in   all   matters   of  work   or 


LUDWIG  AND  MODERN  PHYSIOLOGY.  15 

duty  a  certain  youthfulness  of  disposition  which  made  it 
possible  for  men  much  younger  than  himself  to  accept  his 
friendship.  This  sympathetic  geniality  was,  however,  not 
the  only  or  even  the  chief  reason  why  Ludwig's  pupils  were 
the  better  for  having  known  him.  There  were  not  a  few 
of  them  who  for  the  first  time  in  their  lives  came  into 
personal  relation  with  a  man  who  was  utterly  free  from 
selfish  aims  and  vain  ambitions,  who  was  scrupulously 
conscientious  in  all  that  he  said  and  did,  who  was  what  he 
seemed,  and  seemed  what  he  was,  and  who  had  no  other 
aim  than  the  advancement  of  his  science,  and  in  that  ad- 
vancement saw  no  other  end  than  the  increase  of  human 
happiness.  These  qualities  displayed  themselves  in  Lud- 
wig's daily  active  life  in  the  laboratory,  where  he  was  to  be 
found  whenever  work  of  special  interest  was  going  on  ;  but 
still  more  when,  as  happened  on  Sunday  mornings,  he  was 
"at  home"  in  the  library  of  the  Institute — the  corner  room 
in  which  he  ordinarily  worked.  Many  of  his  "scholars" 
have  put  on  record  their  recollections  of  these  occasions,  the 
cordiality  of  the  master's  welcome,  the  wide  range  and 
varied  interest  of  his  conversation,  and  the  ready  apprecia- 
tion with  which  he  seized  on  anything  that  was  new  or 
original  in  the  suggestions  of  those  present.  Few  men 
live  as  he  did,  "  im  Gaznen,  Gtiten,  Sckonen"  and  of  those 
still  fewer  know  how  to  communicate  out  of  their  fulness  to 
others. 

III.  THE  OLD  AND  THE  NEW  VITALISM. 

Since  the  middle  of  the  century  the  progress  of  Physio- 
logy has  been  continuous.  Each  year  has  had  its  record, 
and  has  brought  with  it  new  accessions  to  knowledge.  In 
one  respect  the  rate  of  progress  was  more  rapid  at  first  than 
it  is  now,  for  in  an  unexplored  country  discovery  is  relatively 
easy.  In  another  sense  it  was  slower,  for  there  are  now 
scores  of  investigators  for  every  one  that  could  be  counted 
in  1840  or  1850.  Until  recently  there  has  been  throughout 
this  period  no  tendency  to  revert  to  the  old  methods — no 
new  departure — no  divergence  from  the  principles  which 
Ludwig  did  so  much  to  enforce  and  exemplify. 


16  SCIENCE  PROGRESS. 

The  wonderful  revolution  which  the  appearance  of  the 
Origin  of  Species  produced  in  the  other  branch  of  Biology, 
promoted  the  progress  of  Physiology,  by  the  new  interest 
which  it  gave  to  the  study,  not  only  of  structure  and  de- 
velopment, but  of  all  other  vital  phenomena.  It  did  not, 
however,  in  any  sensible  degree  affect  our  method  or  alter 
the  direction  in  which  Physiologists  had  been  working  for 
two  decades.  Its  most  obvious  effect  was  to  sever  the  two 
subjects  from  each  other.  To  the  Darwinian  epoch  Com- 
parative Anatomy  and  Physiology  were  united,  but  as  the 
new  Ontology  grew,  it  became  evident  that  each  had  its  own 
problems  and  its  own  methods  of  dealing  with  them. 

The  old  vitalism  of  the  first  half  of  the  century  is  easily 
explained.  It  was  generally  believed  that,  on  the  whole, 
things  went  on  in  the  living  body  as  they  do  outside  of 
it,  but  when  a  difficulty  arose  in  so  explaining  them  the 
Physiologist  was  ready  at  once  to  call  in  the  aid  of  a 
" vital  force' '.  It  must  not,  however,  be  forgotten  that,  as  I 
have  already  indicated,  there  were  great  teachers  (such, 
for  example,  as  Sharpey  and  Allen  Thomson  in  England, 
Magendie  in  France,  Weber  in  Germany)  who  discarded 
all  vitalistic  theories,  and  concerned  themselves  only  with 
the  study  of  the  time-  and  place-relations  of  phenomena  ; 
men  who  were  before  their  time  in  insight,  and  were  only 
hindered  in  their  application  of  chemical  and  physical  prin- 
ciples to  the  interpretation  of  the  processes  of  life  by  the 
circumstance  that  chemical  and  physical  knowledge  was  in 
itself  too  little  advanced.  Comparison  was  impossible,  for 
the  standards  were  not  forthcoming. 

Vitalism  in  its  original  form  gave  way  to  the  rapid  ad- 
vance of  knowledge  as  to  the  correlation  of  the  physical 
sciences  which  took  place  in  the  forties.  Of  the.  many 
writers  and  thinkers  who  contributed  to  that  result,  J.  R. 
Mayer  and  Helmholtz  did  so  most  directly,  for  the  con- 
tribution of  the  former  to  the  establishment  of  the  Doctrine 
of  the  Conservation  of  Energy  had  physiological  considera- 
tions for  its  point  of  departure  ;  and  Helmholtz,  at  the  time 
he  wrote  the  Erhaltung  der  Kraft,  was  still  a  Physiolo- 
gist.     Consequently   when    Ludwig's    celebrated  Lehrbuch 


LUDWIG  AND  MODERN  PHYSIOLOGY.  17 

came  out  in  1852,  the  book  which  gave  the  coup  de grace  to 
vitalism  in  the  old  sense  of  the  word,  his  method  of  setting 
forth  the  relations  of  vital  phenomena  by  comparison  with 
their  physical  or  chemical  counterparts,  and  his  assertion  that 
it  was  the  task  of  Physiology  to  make  out  their  necessary 
dependence  on  elementary  conditions,  although  in  violent 
contrast  with  current  doctrine,  were  in  no  way  surprising  to 
those  who  were  acquainted  with  the  then  recent  progress 
of  research.  Ludwig's  teaching  was  indeed  no  more  than 
a  general  application  of  principles  which  had  already  been 
applied  in  particular  instances. 

The  proof  of  the  non-existence  of  a  special  "  vital  force  " 
lies  in  the  demonstration  of  the  adequacy  of  the  known 
sources  of  energy  in  the  organism  to  account  for  the  actual 
day  by  day  expenditure  of  heat  and  work — in  other  words, 
on  the  possibility  of  setting  forth  an  energy  balance  sheet  in 
which  the  quantity  of  food  which  enters  the  body  in  a  given 
period  (hour  or  day)  is  balanced  by  an  exactly  correspond- 
ing amount  of  heat  produced  or  external  work  done.  It  is 
interesting  to  remember  that  the  work  necessary  for 
preparing  such  a  balance  sheet  (which  Mayer  had  attempted, 
but,  from  want  of  sufficient  data,  failed  in)  was  begun 
thirty  years  ago  in  the  laboratory  of  the  Royal  Institution 
by  the  Foreign  Secretary  of  the  Royal  Society.  But  the 
determinations  made  by  Dr.  Frankland  related  to  one  side  of 
the  balance  sheet,  that  of  income.  By  his  researches  in  1 866 
he  gave  Physiologists  for  the  first  time  reliable  information 
as  to  the  heat  value  {i.e.,  the  amount  of  heat  yielded  by  the 
combustion)  of  different  constituents  of  food.  It  still  re- 
mained to  apply  methods  of  exact  measurement  to  the 
expenditure  side  of  the  account.  Helmholtz  had  estimated 
this,  as  regards  man,  as  best  he  might,  but  the  technical 
difficulties  of  measuring  the  expenditure  of  heat  of  the 
animal  body  appeared  until  lately  to  be  almost  insuperable. 
Now  that  it  has  been  at  last  successfully  accomplished,  we 
have  the  experimental  proof  that  in  the  process  of  life  there 
is  no  production  or  disappearance  of  energy.  It  may  be 
said  that  it  was  unnecessary  to  prove  what  no  scientifically 

sane  man  doubted.     There  are,  however,  reasons  why  it  is 

2 


18  SCIENCE  PROGRESS. 

of  importance  to  have  objective  evidence  that  food  is  the 
sole  and  adequate  source  of  the  energy  which  we  day  by 
day  or  hour  by  hour  disengage,  whether  in  the  form  of  heat 
or  external  work. 

In  the  opening  paragraph  of  this  section  it  was  observed 
that  until  recently  there  had  been  no  tendency  to  revive  the 
vitalistic  notion  of  two  generations  ago.  In  introducing  the 
words  in  italics  I  referred  to  the  existence  at  the  present 
time  in  Germany  of  a  sort  of  reaction,  which  under  the 
term  "  Neovitalismus  "  has  attracted  some  attention — -so 
much  indeed  that  at  the  Versani7nlung  Deutscher  Natur- 
forscher  at  Ltibeck  last  September,  it  was  the  subject  of 
one  of  the  general  addresses.  The  author  of  this  address, 
Prof.  Rindfleisch,  was,  I  believe,  the  inventor  of  the  word  ; 
but  the  origin  of  the  movement  is  usually  traced  to  a  work 
on  Physiological  Chemistry  which  an  excellent  translation 
by  the  late  Dr.  Wooldridge  has  made  familiar  to  English 
students.  The  author  of  this  work  owes  it  to  the  language 
he  employs  in  the  introduction  on  "  Mechanism  and 
Vitalism,"  if  his  position  has  been  misunderstood,  for  in 
that  introduction  he  distinctly  ranges  himself  on  the  vital- 
istic side.  As,  however,  his  vitalism  is  of  such  a  kind  as 
not  to  influence  his  method  of  dealing  with  actual  problems, 
it  is  only  in  so  far  of  consequence  as  it  may  affect  the  reader. 
For  my  own  part  I  feel  grateful  to  Professor  Bange  for 
having  produced  an  interesting  and  readable  book  on  a  dry 
subject,  even  though  that  interest  may  be  partly  due  to  the 
introduction  into  the  discussion  of  a  question  which,  as  he 
presents  it,  is  more  speculative  than  scientific. 

As  regards  other  physiological  writers  to  whom  vitalistic 
tendencies  have  been  attributed,  it  is  to  be  observed  that 
none  of  them  have  even  suggested  that  the  doctrine  of  a 
"vital  force"  in  its  old  sense  should  be  revived.  Their 
contention  amounts  to  little  more  than  this,  that  in  certain 
recent  instances  improved  methods  of  research  appear  to 
have  shown  that  processes  at  first  regarded  as  entirely 
physical  or  chemical  do  not  conform  so  precisely  as  they 
were  expected  to  do  to  chemical  and  physical  laws.  As 
these  instances  are  all  essentially  analogous,  reference  to 
one  will  serve  to  explain  the  bearing  of  the  rest. 


LUDWIG  AND  MODERN  PHYSIOLOGY.  19 

Those  who  have  any  acquaintance  with  the  structure  of 
the  animal  body  will  know  that  there  exists  in  the  higher 
animals,  in  addition  to  the  system  of  veins  by  which  the 
blood  is  brought  back  from  all  parts  to  the  heart,  another 
less  considerable  system  of  branched  tubes,  the  lymphatics, 
by  which,  if  one  may  so  express  it,  the  leakage  of  the  blood- 
vessels is  collected.  Now,  without  inquiring  into  the  why 
of  this  system,  Ludwig  and  his  pupils  made  and  continued 
for  many  years  elaborate  investigations  which  were  for  long 
the  chief  sources  of  our  knowledge,  their  general  result 
being  that  the  efficient  cause  of  the  movement  of  the  lymph, 
like  that  of  the  blood,  was  mechanical.  At  the  Berlin  Con- 
gress in  1890  new  observations  by  Professor  Heidenhain  of 
Breslau  made  it  appear  that  under  certain  conditions  the 
process  of  lymph  formation  does  not  go  on  in  strict  accord- 
ance with  the  physical  laws  by  which  leakage  through 
membranes  is  regulated,  the  experimental  results  being  of 
so  unequivocal  a  kind  that,  even  had  they  not  been  con- 
firmed, they  must  have  been  received  without  hesitation. 
How  is  such  a  case  as  this  to  be  met?  The  "Neovitalists  " 
answer  promptly  by  reminding  us  that  there  are  cells,  i.e., 
living  individuals,  placed  at  the  inlets  of  the  system  of 
drainage  without  which  it  would  not  work,  that  these  let  in 
less  or  more  liquid  according  to  circumstances,  and  that  in 
doing  so  they  act  in  obedience,  not  to  physical  laws,  but  to 
vital  ones — to  internal  laws  which  are  special  to  themselves. 

Now,  it  is  perfectly  true  that  living  cells,  like  working 
bees,  are  both  the  architects  of  the  hive  and  the  sources  of 
its  activity,  but  if  we  ask  how  honey  is  made  it  is  no  answer 
to  say  that  the  bees  make  it.  We  do  not  require  to  be  told 
that  cells  have  to  do  with  the  making  of  lymph  as  with 
every  process  in  the  animal  organism,  but  what  we  want  to 
know  is  how  they  work,  and  to  this  we  shall  never  get  an 
answer  so  long  as  we  content  ourselves  with  merely  ex- 
plaining one  unknown  thing  by  another.  The  action  of 
cells  must  be  explained,  if  at  all,  by  the  same  method  of 
comparison  with  physical  or  chemical  analogues  that  we 
employ  in  the  investigation  of  organs. 

Since   1890  the  problem  of  lymph  formation  has  been 


20  SCIENCE  PROGRESS. 

attacked  by  a  number  of  able  workers,  among  others  here 
in  London,  by  Dr.  Starling  of  Guy's  Hospital,  who,  by 
sedulously  studying  the  conditions  under  which  the  dis- 
crepancies between  the  actual  and  the  expected  have  arisen, 
has  succeeded  in  untying  several  knots.  In  reference  to 
the  whole  subject,  it  is  to  be  noticed  that  the  process  by 
which  difficulties  are  brought  into  view  is  the  same  as  that 
by  which  they  are  eliminated.  It  is  one  and  the  same 
method  throughout,  by  which  step  by  step,  knowledge  per- 
fects itself — at  one  time  by  discovering  errors,  at  another 
by  correcting  them  ;  and  if  at  certain  stages  in  this  pro- 
gress difficulties  seem  insuperable,  we  can  gain  nothing  by 
calling  in,  even  provisionally,  the  aid  of  any  sort  of  Eidolon, 
whether  "cell,"  "protoplasm"  or  internal  principle. 

It  thus  appears  to  be  doubtful  whether  any  of  the 
biological  writers  who  have  recently  professed  vitalistic 
tendencies  are  in  reality  vitalists.  The  only  exception 
that  I  know  is  to  be  found  in  the  writings  of  a  well- 
known  morphologist,  Dr.  Hans  Driesch,1  who  has  been 
led  by  his  researches  on  what  is  now  called  the  Me- 
chanics of  Evolution  to  revert  to  the  fundamental  con- 
ception of  vitalism,  that  the  laws  which  govern  vital 
processes  are  not  physical,  but  biological — that  is,  peculiar 
to  the  living  organism,  and  limited  thereto  in  their 
operation.  Dr.  Driesch's  researches  as  to  the  modifi- 
cations which  can  be  produced  by  mechanical  inter- 
ference in  the  early  stages  of  the  process  of  ontogenesis 
have  enforced  upon  him  considerations  which  he  evidently 
regards  as  new,  though  they  are  familiar  enough  to  Physio- 
logists. He  recognises  that  although  by  the  observation  of 
the  successive  stages  in  the  ontogenetic  process,  one  may 
arrive  at  a  perfect  knowledge  of  the  relation  of  these  stages 
to  each  other,  this  leaves  the  efficient  causes  of  the  develop- 
ment unexplained  [fukrt  nicht  zu  einem  Erkenntniss  ihrer 
bewirkenden    Ursacheii)- — it    does    not    teach    us   why    one 

1  Driesch.  "  Entwicklungsmechanische  Studien  "  :  a  series  of  ten 
Papers,  of  which  the  first  six  appeared  in  the  Zeitsch.  /.  w.  Zoologie,  vols, 
liii.  and  lv. ;  the  rest  in  the  Mittheihingen  of  the  Naples  Station. 


LUDWIG  AND  MODERN  PHYSIOLOGY.  21 

form  springs  out  of  another.  This  brings  him  at  once  face 
to  face  with  a  momentous  question.  He  has  to  encounter 
three  possibilities  —  he  may  either  join  the  camp  of  the 
biological  agnostics  and  say  with  du  Bois-Reymond,  "ignora- 
mus et  ignorabimus"  or  be  content  to  work  on  in  the  hope 
that  the  physical  laws  that  underlie  and  explain  organic 
Evolution  may  sooner  or  later  be  discovered,  or  he  may 
seek  for  some  hitherto  hidden  Law  of  Organism  of  which 
the  known  facts  of  Ontogenesis  are  the  expression,  and 
which,  if  accepted  as  a  Law  of  Nature,  would  explain  every- 
thing. Of  the  three  alternatives  Driesch  prefers  the  last, 
which  is  equivalent  to  declaring  himself  an  out  and  out 
vitalist.  He  trusts  by  means  of  his  experimental  investiga- 
tions of  the  Mechanics  of  Evolution  to  arrive  at  "  elementary 
conceptions"  on  which  by  "mathematical  deduction"1  a 
complete  theory  of  Evolution  may  be  founded. 

If  this  anticipation  could  be  realised,  if  we  could  con- 
struct with  the  aid  of  those  new  Principia  the  ontogeny  of 
a  single  living  being,  the  question  whether  such  a  result 
was  or  was  not  inconsistent  with  the  uniformity  of  Nature, 
would  sink  into  insignificance  as  compared  with  the 
splendour  of  such  a  discovery. 

But  will  such  a  discovery  ever  be  made  ?  It  seems  to 
me  even  more  improbable  than  that  of  a  physical  theory 
of  organic  evolution.  It  is  satisfactory  to  reflect  that  the 
opinion  we  may  be  led  to  entertain  on  this  theoretical 
question  need  not  affect  our  estimate  of  the  value  ol  Dr. 
Driesch's  fruitful  experimental  researches. 

J.   Burdon  Sanderson. 

1  "  Elementarvorstellungen  .  .  .  die  zwar  mathematische  Deduktion 
aller  Erscheinungen  aus  sich  gestatten  mochten."  Driesch.  "  Beitrage 
zur  theoretischen  Morphologic"     Biol.  Centralblatt,  vol.  xii.,  p.  539,  1892. 


ON    RECENT    ADVANCES    IN    VEGETABLE 

CYTOLOGY. 

PART  I. 

DURING  the  last  quarter  of  a  century  a  considerable 
change  has  passed  over  the  aspect  of  biology, 
especially  in  this  country.  It  was  formerly  possible  for  a 
man  to  be,  fairly  at  any  rate,  well  up  in  the  two  branches 
of  zoology  and  botany,  but  this  is  no  longer  possible, 
regarded  from  our  modern  standpoint.  Specialisation, 
inevitable  owing  to  the  rapid  advances  which  have  been 
everywhere  made,  has  not  only  effected  a  practical 
divorce  between  these  two  sciences,  but  the  same  disrupting 
agency  is  operating  continuously  in  each  of  them. 

None  the  less  is  it  true,  however,  that  there  are  certain 
features  of  fundamental  importance  which  are  shared  alike 
by  animals  and  plants.  This  community  of  structure  is 
most  clearly  recognised  within  the  limits  of  the  individual 
cells,  and  it  is  perhaps  nowhere  more  impressively  demon- 
strated than  in  the  remarkable  similarity  which  exists 
between  the  nuclear  division  as  observed  in  animals  and  in 
plants, — a  similarity  which  may  extend  to  the  most  minute 
details. 

The  cell,  using  the  word  in  its  widest  sense,  is,  as 
Haeckel  said  long  ago,  emphatically  the  unit  of  life.  For 
though  the  several  parts,  such  as  nucleus  and  the  cell- 
protoplasm,  which  together  constitute  a  cell,  all  possess 
autonomy  to  a  certain  degree,  it  still  remains  true  that  it  is 
only  when  they  operate  jointly  and  in  harmony  that  a  suc- 
cessful and  "going  concern,"  a  living  individual,  is  the 
result.  And  since  we  have  strong  reasons  for  believing 
that  animals  and  plants  represent  the  diverging  limbs  of  a 
stock  traceable  at  the  root  to  a  common  source,  viz.,  lowly 
unicellular  organisms,  it  is  obvious  that  the  study  of  the  cell, 
of  its  structure  and  of  the  functions  discharged  by  its 
various  parts,  offers  an  immensely  important,  though  it 
may  well  be  a  very  difficult,  field  for  research. 


RECENT  ADVANCES  IN  VEGETABLE  CYTOLOGY.  23 

What,  we  may  ask,  is  the  essential  structure  of  the 
protoplasm,  of  the  nucleus,  and  of  those  marvellous  bodies, 
the  chromosomes,  which  reappear  at  every  nuclear  division  ? 
What  is  it  that  initiates  the  division  of  a  cell  or  of  its 
nucleus,  and  why  do  some  cells  go  through  such  complex 
evolutions  whilst  others  seem  to  adopt  a  relatively  simple 
course?  What  is  it  that  determines  that  the  descendants  of 
one  cell  shall  develop  differently  from  those  of  another,  so 
as  to  give  rise  to  this  or  that  tissue  system  ?  Or  again, 
how  is  the  unicellular  condition  of  an  infusorian  compatible 
with  an  intricate  and  often  highly  differentiated  organisa- 
tion ? 

These  and  a  host  of  other  questions  rise  and  confront 
us  on  the  very  threshold  of  our  inquiry,  and  the  hints  which 
Nature  has  dropped  for  our  guidance  are  at  best  only 
obscure  ones  ;  thus  the  position  of  the  biological  investigator 
contrasts  unfavourably  with  that  of  the  chemist  or  physicist, 
inasmuch  as  he  is  generally  debarred,  owing  to  the  very 
conditions  of  the  bodies  he  is  dealing  with,  from  having 
recourse  to  direct  experiment ;  Nature  conducts  the  experi- 
ments and  he  has  to  remain  content  with  watching-  the 
result,  analysing  the  factors  and  reconstructing  the  process 
as  best  he  can.  Nevertheless  there  is,  clearly,  no  funda- 
mental distinction  between  the  (so-called)  observational 
and  experimental  sciences. 

It  is,  then,  only  by  patient  accumulation  and  careful 
comparison  of  all  the  facts  that  even  a  proximate  solution 
of  the  difficulties  before  us  can  ever  be  reached.  Much 
has  been  done  in  collecting  the  data,  and  a  good  deal  is 
known  both  as  to  the  structure  of  the  cell  and  the  phases 
through  which  it  passes  during  its  existence.  And  fortu- 
nately one  generalisation  is  gradually  emerging  with  in- 
creasing clearness  from  beneath  the  ever-growing  pile  of 
detail,  and  it  promises  to  prove  a  guide  of  no  small  value, 
namely,  that  in  those  processes  which  we  have  reason  to 
regard  as  fundamentally  important  there  exists  a  surprising 
degree  of  similarity  between  the  structural  elements  of 
animals  on  the  one  hand  and  of  plants  on  the  other.  And 
these  points  of  similarity  are  now  known  to  be  so  numerous 


24  SCIENCE  PROGRESS. 

and  so  close  that  we  are  almost  warranted  in  drawing  the 
conclusion  that  the  measure  of  the  resemblance  will  afford  a 
criterion  as  to  the  relative  degree  of  importance  to  be 
attached  to  this  or  that  phenomenon  of  cell  life. 

It  seems  almost  certain  that  this  similarity  is  to  be 
interpreted  as  the  result  of  the  evolution  along  parallel 
lines  of  a  particular  structural  arrangement,  or,  to  put  it  in 
another  way,  as  being  the  outcome  of  the  continuous  opera- 
tion of  similar  forces  upon  an  essentially  similar  proto- 
plasmic structure.  No  doubt  all  the  change  manifested  in 
protoplasm  is  ultimately  to  be  ascribed  to  the  effects  of 
forces  upon  its  own  material  substance  ;  the  special  point 
of  interest  here  lies  in  the  similarity  of  the  results.  It 
cannot  be  due  to  mere  accident  that  the  stages  in  the  develop- 
ment of  the  spermatozoa  of  a  newt  should  bear  a  closer 
resemblance  to  the  corresponding  divisions  in  the  pollen- 
mother-cell  of  a  lily  than  they  do  to  the  rest  of  the  tissue 
cells  in  the  body  of  the  same  newt. 

In  the  present  article  it  is  not  my  purpose  to  attempt  to 
summarise  the  vast  amount  of  detail  which  has  accumulated 
within  recent  years  ;  my  aim  is  rather  to  try  to  indicate  the 
general  directions  in  which  the  results  seem  to  be  tending, 
and  to  point  out  the  kind  of  evidence  on  which  the  current 
views  are  based.  And  although  I  am  here  especially  dealing 
with  the  botanical  aspect  of  the  questions  involved,  it  will 
be  clear  from  what  has  been  already  said  that  it  will  be 
impossible,  and  certainly  not  desirable,  to  ignore  the  in- 
vestigations which  have  been  prosecuted  by  the  zoologists. 

And  in  order  to  make  clear  that  which  is  to  follow,  it 
may  not  be  superfluous  to  recapitulate  the  general  relations 
of  nucleus  and  cell  protoplasm  as  commonly  received  at  the 
present  time.  The  essential  character  of  all  cells,  whether 
animal  or  vegetable,  and  whether  they  exist  as  free  inde- 
pendent organisms,  or  whether  they  form  more  or  less 
highly  differentiated  colonies,  consists  in  this,  the  association 
of  a  nucleus  with  a  certain  amount  of  cell  protoplasm  (com- 
monly called  Cytoplasm,  to  distinguish  it  from  the  nuclear 
protoplasm).  And  this  is  equally  true,  so  far  as  we  have 
means  of  determining  the   question,    in   the   case   of  those 


RECENT  ADVANCES  IN  VEGETABLE  CYTOLOGY.  25 

organisms  in  which  we  as  yet  have  failed  to  recognise  a  de- 
finite nuclear  body,  for  there  are  reasons  for  believing  that  the 
nuclear  substance  is  in  all  cases  really  present,  whether  it 
happens  to  be  collected  into  a  specialised  mass  or  not.  And 
it  should  be  remembered  that  the  number  of  cells  supposed 
to  possess  what  we  may  term  a  distributed  or  discrete 
nucleus  is  becoming  smaller  as  our  means  of  investigations 
improve.  Thus  according  to  Wager  ( 1 )  even  Bacteria 
possess  a  true  nucleus. 

I  am  perfectly  aware  that  attacks  have  recently  been 
made  on  the  cell-theory  as  extended  to  explain  the  organisa- 
tion (Whitman,  Sedgwick)  of  animals,  and  that  nobody 
would  assert  the  cell  to  the  ultimate  unit  of  living  substance. 
But  neither  of  these  propositions  really  affects,  or  is  con- 
cerned with,  the  point  of  view  just  now  before  us.  We  are 
not  here  dealing  with  the  wide  questions  connected  with  the 
architecture  of  the  organism  as  a  whole,  nor  with  the 
equally  difficult  one,  as  to  what  constitutes  the  ultimate 
units  of  living  matter,  rather  we  are  content  just  now  to 
study  the  interaction  of  the  parts  which  together  are  capable 
of  carrying  on  a  continuous  living  existence,  which  form  a 
living  individual,  and  these  parts  consist  jointly  of  the 
nucleus  and  its  surrounding  cytoplasm.1  The  occurrence  of 
cell  walls  is  a  matter  of  no  importance  from  a  general  stand- 
point, although  when  present  they  may  profoundly  modify 
the  characters  of  the  organism  in  which  they  are  formed. 
Many  plants  are  known  in  which  the  protoplasm  is  only 
delimited  by  a  cell  wall  from  the  surrounding  medium,  while 
the  oftentimes  huge  protoplasmic  mass  suffers  no  internal 
partitioning,  although  it  contains  a  vast  number  of  nuclei 
distributed  through  it. 

Sachs,  with  characteristic  insight,  long  ago  perceived 
that  the  presence  or  absence  of  cell  walls  is  a  matter  of 
only  secondary  importance.  Their  sequence  and  arrange- 
ment at  the  time  of  their  first  appearance  can  be  predicted 

1  The  researches  of  Klebs,  Acqua,  and  others  have  shown  that  although 
protoplasm  deprived  of  a  nucleus  may  sometimes  even  assimilate  food  and 
maintain  life  for  a  not  inconsiderable  period  of  time,  it  is  incapable  of 
division. 


26  SCIENCE  PROGRESS. 

from  simple  geometrical  considerations  quite  independently 
of  the  ultimate  form  which  will  be  finally  assumed  as 
the  result  of  specialised  growth.  And  in  applying  the  word 
Non-cellular  to  those  plants  in  which  partition  walls  do  not 
occur,  he  merely  gives  formal  expression  to  the  fact  that 
these  anatomical  structures  are  absent,  although  in  other 
respects  the  plants  in  question  conform  with  those  usually 
called  multicellular,  and  they  are  not  at  all  to  be  regarded  as 
consisting  of  a  single  enlarged  cell.  In  fact  he  has  expressly 
stated  that  non-cellular  plants  are  really  the  equivalent  of 
multicellular  organisms  in  which  the  formation  of  internal 
cell  walls  does  not  occur.  More  recently  he  has  introduced 
the  term  Energid  (2)  to  express  the  physiological  individu- 
ality of  those  units  I  have  here  continued  to  call  cells,  and 
he  thereby  emphasises  the  fact  of  their  real  existence 
whether  any  positive  anatomical  boundaries  can  be  dis- 
cerned between  them  or  not. 

It  must  however  be  clearly  understood  that  in  formulat- 
ing  the  expression  energid,  Sachs  lays  especial  stress  on 
the  dynamical  aspect  of  the  relations  existing  between  the 
cytoplasm  and  the  nucleus.  But  it  will  be  admitted  by  most 
people  that  a  conception  of  force  apart  from  the  material 
substance  on  or  through  which  it  acts,  and  by  which  its 
operation  becomes  perceptible  to  the  senses,  belongs  to  the 
domain  of  purely  abstract  ideas.  We  require  to  know  far 
more  of  the  nature  and  structure  of  protoplasm  before  we 
can  usefully  divorce  our  conceptions  of  force  from  our  ex- 
perience of  matter  in  attempting  to  ascertain  the  nature 
of  those  physiological  causes  of  which  all  external  form  is 
but  the  outward  and  visible  sign.  Sachs  himself,  however, 
escapes  the  charge  of  vagueness,  by  restricting  the  applica- 
tion of  his  expression  so  as  to  impose  a  territorial  limit  to 
the  sphere  of  influence  mutually  existing  between  each 
nucleus  and  the  surrounding  cytoplasm.  For  him  the  word 
Energid  embodies  the  idea  that  the  whole  protoplasmic 
region  is  partitioned  into  smaller  provinces  each  dominated 
by  its  own  nucleus.  And  although  it  may  be  advantageous 
for  the  seprovinces  to  be  delimited  from  each  other  by  cell 
walls,  permitting  thereby  a  more  complete  independence  to 


RECENT  ADVANCES  IN  VEGETABLE  CYTOLOGY.  27 

attach   to   each   one  severally,  the  existence  of  such  well- 
defined  boundaries  is  by  no  means  an  indispensable  condition 
of  great  complexity  of  organisation.      Caulerpa  amongst  the 
algae  imitates  very  closely  the  differentiated   form  of  some 
of  the  higher  terrestrial  plants,  without  however  possessing 
their  corresponding   internal   structure.      Its   protoplasm   is 
bounded  by   an   external  wall   only,  and  is   not   internally 
partitioned.        And   yet    the   characters    distinctive    of  the 
energids  in  the  leaf-like  parts  are  assuredly  different  from 
those  of  the  energids  which  exist  in  the  creeping  stem  or 
rootlike  fibres.     A  transition  from  the  condition  of  Caulerpa 
to  that  of  the  higher  plants  may  be  seen  in   Cladophora,  in 
which  the  filamentous  body  seems,  at  first  sight,  to  be  made 
up   of  chains   of  cells,  each   of  which  stands  in   a   definite 
relation    to   the   general  symmetry  of  the   branched  plant  ; 
nevertheless,  closer  examination  shows  that  each  "cell"  is 
multi-nucleate,  and  really  represents  a  federation  of  energids 
which  so  act  together  as  to  constitute  morphological  units  as 
far  as  the  external  form  of  the  plant  as  a  whole  is  concerned. 
Sachs'  conception  of  the  energid  has  been  assailed  by 
some  writers,  and  he  has  to  some  extent  perhaps  invited 
criticism  by  formerly  affixing  a  quasi-morphological,  as  well 
as  a  physiological  significance  to  the  term.      At  first  sight 
it  may  seem  difficult  to  justify  its  application  in  those  cases 
in  which  streaming  movement  happens  to  go  on  in  certain 
layers   of  the   protoplasm,    whilst   the   layer   in   which   the 
nuclei  are  embedded  is  at  rest.      It  is  obvious  that  if  we 
admit,  as  we  can  hardly  avoid  doing,  that  the  nucleus  does 
really   exert    a  directive  action   over  a  localised  area,    the 
migratory  protoplasm  (assuming  the  movement  to  affect  the 
protoplasm,  and  not  merely  the  granular  bodies  contained 
in    it)    must    be    constantly    coming    within    the    range    of 
fresh   centres  of  influence.      It  may  perhaps  be  compared 
to  the  case  of  a   person   passing   from   a   region   presided 
over    by    one    government    into    one    under    the    jurisdic- 
tion of  another.     Such  a  person  would  naturally  be  subjected 
to  changed  conditions,  without  however  affecting  either  his 
own  identity  or  that  of  the  particular  political  centres  through 
which  he  may  happen  to  travel. 


28  SCIENCE  PROGRESS. 

Strasburger  (3)  has  attempted  to  define  more  clearly  the 
position  of  the  individual  energid,  by  proposing  to  limit  its 
application  to  the  nucleus  together  with  a  special  part  of  the 
cytoplasm  which  he  calls  Kinoplasm  and  which  he  regards 
as  the  proximate  seat  of  the  effective  manifestation  of  the 
forces  at  work  in  the  cell.  He  regards  the  nomadic 
streaming  protoplasm  as  being  mainly  charged  with  the 
function  of  providing  nourishment  for  the  nucleus  and 
kinoplasm,  and  he  distinguishes  it  by  the  special  term  of 
Trophoplasm.  Strasburger  maintains  this  same  distinction 
between  the  active  Kinoplasm  and  the  nutritive  tropho- 
plasm in  those  cases  in  which  the  limits  of  the  several 
energids  correspond  with  those  of  the  individual  cells ; 
and  in  this  he  is  logical  enough,  for  we  know  that  living 
cells  are  not  isolated  from  each  other,  but  that  protoplasmic 
continuity  exists  between  adjacent  cells  by  means  of  pores 
in  the  intervening  walls.  How  far  the  distinction  between 
kinoplasm  and  trophoplasm  is  either  justified  by  observa- 
tion or  demanded  by  theory  is  another  matter  altogether. 

But  although  the  conception  of  energids  is  a  happy  one, 
as  enabling  us  to  distinguish  discrete  individualities  in  what 
may  at  first  sight  appear  to  consist  of  a  common  structure, 
it  is  not  to  be  inferred  that  the  individuals  enjoy  independ- 
ence. The  great  merit  of  the  idea  lies  in  the  fact  that  it 
serves  to  narrow  down,  and  hence  to  render  more  clearly 
comprehensible,  many  important  problems  which  call  for  a 
solution  before  we  can  hope  to  grapple  successfully  with 
the  more  advanced  questions  relating  to  those  forces  of  a 
still  higher  order  which  control  and  apparently  direct  the 
development  of  the  organism  as  a  whole,  or  to  put  it  in 
another  way,  which  determine  the  course  of  development 
which  the  particular  energids  shall  follow.  Such  control  is 
plainly  apparent  at  every  stage  in  the  life  of  an  organism. 
Why  does  growth  take  place  symmetrically  so  that  the 
energids,  cells,  or  whatever  we  may  choose  to  call  them,  so 
act  in  unison  as  to  produce  a  "  body  fitly  joined  together 
and  compacted  by  that  which  every  joint  supplieth,  accord- 
ing to  the  effectual  working  in  the  measure  of  every 
part "  ?      Without      some     such     assumption     how     is     it 


RECENT  ADVANCES  IN  VEGETABLE  CYTOLOGY.  29 

possible  to  account  for  the  fact  that  in  certain  embryos 
which  have  been  mutilated,  the  surviving  cells  are  enabled 
to  so  modify  the  course  of  their  normal  development  as 
to  make  good  the  loss,  and  thus  to  form  a  perfect,  if 
somewhat  miniature  organism  ?  For  had  there  been  no 
mutilation  the  cells  thus  concerned  would  unquestion- 
ably not  have  developed  in  the  same  way,  but  would  have 
fulfilled  the  allotted  task  of  merely  providing  for  the  genesis 
of  their  normal  tissue  products.  Or  again,  why  is  it  that 
when  a  lizard's  tail  is  broken  off  the  general  form  of  the 
entire  animal  is  once  more  reproduced,  even  though  there 
are  important  histological  and  structural  (but  probably  not 
functional)  differences  in  the  new  tail  as  compared  with 
that  of  the  original  one  (4)  ? 

When  differentiation  has  so  far  become  manifested  in 
an  organism  that  the  limits  of  the  several  energids  are 
coterminous  with  the  cell  walls,  a  considerable  increase  in 
their  degree  of  independence  doubtless  ensues,  but  it  is,  as 
already  stated,  by  no  means  absolute,  and  the  examples  just 
quoted  support  the  statement.  Whether  organisation  is 
the  result  of,  or  the  factor  which  determines,  the  co-ordi- 
nate action  of  the  cells  is  a  question  which  we  may  safely 
leave  to  the  future  to  decide.  But  perhaps  it  may  be 
permissible  to  compare  the  cell  colony  which  forms  the 
organism  to  an  isolated  society  in  which  the  caste  system 
prevails.  Each  caste  or  cell  group  is  predestined  to  dis- 
charge certain  definite  offices  in  the  state  or  the  organism. 
If  some  indispensable  caste  should  become  exterminated,  it  is 
obvious  that  a  differentiation  and  displacement  must  occur 
amongst  those  which  survive,  and  this  differentiation 
might  either  be  readily  complete,  or  it  might  only  arise  as 
a  reluctant  concession  to  necessity,  just  as  a  willow  twig 
planted  upside  down  in  damp  soil  will  form  roots  at  this,  its 
upper,  end  ;  though  comparison  with  a  twig  planted  with 
its  basal  end  in  the  ground  will  show  how  severe  a  tax  the 
unusual  effort  has  proved. 

It  has  already  been  said  that  an  energid,  and  it  might 
also  be  added,  a  typical  cell,  consists  essentially  of  a  nucleus 
and  the  protoplasm  included  within  a  certain   area  around 


30  SCIENCE  PROGRESS. 

it.  But  we  cannot  as  yet  answer  the  more  obvious  and,  one 
might  think,  almost  preliminary  question  as  to  what  the 
chief  functions  which  are  discharged  by  these  two  com- 
ponents really  may  be.  It  is  certain  that  the  existence  of  a 
nucleus  is  essential  to  morphological  development  such  as  is 
implied  in  the  production  of  new  cells,  and  very  probably 
also  in  the  further  differentiation  of  those  which  have 
already  been  formed.  Instances  of  this  are  seen  for  example 
in  the  growth  or  alteration  of  the  cell  wall.  Haberlandt 
(5)  some  years  ago  drew  special  attention  to  the  fact 
that  when  local  thickening  occurred  in  a  cell  wall  the 
nucleus  commonly  moved  to  this  spot,  and  the  present 
writer  has  repeatedly  observed  it  during  the  formation  of 
the  hard  coat  found  on  many  seeds  ;  here  the  deposition  of 
substance  is  usually  localised  on  the  inner  parts  of  the  cell, 
and  the  nucleus  takes  up  a  corresponding  position  as  soon 
as  the  process  begins.  Korschelt  (6)  has  observed  a 
similar  relation  to  exist  during  the  chitinisation  of  the  mem- 
branes of  insect  cells,  and  quite  recently  Istvanffi  (Ber.  Deut. 
Gesel.,  Dec,  1895)  has  observed  that  when  the  tubular 
hypha  of  Mucor  branches,  a  nucleus  is  invariably  present  at 
the  spot  whence  the  branch  is  arising.  Strasqurger  (3^)  has 
also  drawn  attention  to  the  same  truth,  inasmuch  as  he 
states  that  before  the  opening  of  the  zoosporangium  of 
CEdogonium,  the  nucleus  and  kinoplasm  aggregate  in  the 
vicinity  of  the  spot  at  which  the  hole  is  about  to  be  formed. 

But  perhaps  one  of  the  most  striking  instances  of  the 
directive  effect  of  the  nucleus  as  a  whole  is  to  be  seen  in 
the  result  of  an  experiment  of  Boveri,  who  asserts  that  he 
impregnated  a  non-nucleated  piece  of  protoplasm  of  an 
echinoderm  ovum  with  the  sperm  nucleus  of  another  species ; 1 
development  ensued,  and  the  larva  resembled  the  paternal 
form  (7). 

In  discussing  the  relations  which  exist,  or  are  supposed 
to  exist,  between  the  cytoplasm  and  the  nucleus,  it  is  clearly 
of  the  first  importance  to  know  what  are  the  changes  which 
occur   in  them,  and   especially   in    the   nucleus,    during   the 

1  The  animals  actually  employed  were  Echinus  microtuberculatus 
(male),  and  Sphaerechinus  granulans  (female). 


RECENT  ADVANCES  IN  VEGETABLE  CYTOLOGY.  31 

growth,  maturity  and  senescence  of  the  cells.  Some  ex- 
tremely interesting  results  in  this  direction  have  recently  been 
published  by  Zacharias  (8).  An  ordinary  resting  nucleus 
consists,  as  all  biologists  are  aware,  of  a  somewhat  dense 
thread-like  framework,  often  spoken  of  as  linin,  which 
usually  exhibits  copious  anastomosis,  sometimes  to  such  a 
degree  that  it  almost  forms  a  spongy  texture.  In  this 
framework  granules  are  found  embedded  which  react 
definitely  to  stains  and  to  solvents  ;  they  constitute  the 
nuclein,  a  phosphorus-containing  substance  which  at  the 
periods  of  nuclear  division  undergoes  an  enormous  increase 
in  bulk.  The  linin  is  bathed  in  a  more  fluid  substance,  the 
paralinin.  One  or  more  spherical  bodies,  the  nucleoli, 
are  often  present  in  addition  to  the  foregoing  constituents, 
and  the  nucleus  is  delimitated  from  the  cytoplasm  by  a 
pellicle  or  membrane.  The  nucleolus  contains,  as  was 
shown  by  Zacharias  many  years  ago,  at  least  two 
substances,  one  of  which  is  of  an  albuminous  nature,  and  is 
dissolved  out  on  treatment  with  gastric  juice  ;  after  peptic 
digestion  has  extracted  the  albumin,  a  substance  is  left 
which  Zacharias  calls  Plastin.  Now  observation  shows 
that  the  relative  proportion  of  these  two  constituents  varies 
considerably  at  different  periods  of  the  life  of  the  cell,  and 
this  is  of  importance  in  connection  with  the  intricate  series 
of  changes  which  the  nucleus  passes  through  during  the 
process  of  ordinary  division.  The  conviction  has  slowly 
been  forced  upon  us  within  the  last  few  years  that  there 
exists  a  considerable  variety  amongst  the  bodies  which 
have  been  included  in  the  common  term  of  nucleoli. 
Auerbach  (9)  showed  in  1890  that  some  of  them 
absorbed  certain  red  dyes  with  greater  avidity  than  they  did 
certain  blue  ones,  whilst  other  nucleoli  reacted  in  the  oppo- 
site manner.  He  thus  distinguished  between  erythrophil 
and  cyanophil  nucleoli.  These  results  have  been  extended 
to  plants  by  the  investigations  of  Rosen  (10)  and  others, 
but  especially  by  Zacharias,  who  has  applied  the  test  of 
solvents  to  them,  with  the  result  that  the  difference  between 
the  two  classes  of  nucleoli  proves  to  be  a  much  more  real 
one  than  had  hitherto  been  supposed.      And  these  observa- 


32  SCIENCE  PROGRESS. 

tions  are  specially  interesting  when  considered  from  the 
point  of  view  of  the  great  dissentience  of  opinion  which  exists 
between  most  botanists  and  zoologists  as  to  the  nature  and 
function  of  the  nucleolus.  Strasburger,  who  admitted  the  cor- 
rectness of  Rosen's  statements,  considered  that  the  difference 
between  an  erythrophil  and  a  cyanophil  nucleus  was  largely 
one  of  nutrition,  and  he  instanced  in  support  of  his  view 
the  difference  between  the  erythrophil  nucleolus  in  the 
nucleus  of  the  well-nourished  oosphere  and  the  cyanophil 
nucleus  of  the  much  smaller,  and  therefore  presumably 
worse  nourished  generative  cell  of  the  pollen  tube.  But 
Zacharias,  in  criticising  Strasburger's  views,  considers  that 
there  is  no  evidence  to  prove  that  the  one  nucleolus  is  in  a 
better  position  than  another  as  regards  its  nutrition,  and  it 
is  still  more  difficult  to  accept  the  suggested  explanation  in 
those  cases  in  which  both  forms  of  nucleoli  are  concomi- 
tantly present. 

Zacharias  has  shown  that  whereas  the  erythrophil 
nucleoli  contain  albumin  and  plastin,  the  cyanophil  kind 
(the  "pseudo-nucleoli"  of  Rosen  and  others)  contain  nuclein, 
a  substance  quite  absent  from  the  other  class  of  nucleoli. 
Rosen  in  1892  stated  his  conviction  that  his  pseudo-nucleoli 
in  reality  consisted  of  chromatic  substance  (nuclein)  and 
that  they  contribute  to  the  formation  of  those  remarkable 
bodies,  the  chromosomes,  which  are  evolved  by  the  break- 
ing up  of  the  linin  framework  after  the  amount  of  nuclein 
has  greatly  increased  in  it,  previous  to  the  division  of  the 
nucleus.  Now  the  nucleolus  exhibits  striking  chancres  both 
during  the  growth,  and  also  during  the  division  of  the  cell  and 
its  nucleus.  As  regards  the  behaviour  during  cell  growth,  the 
relation  of  the  nucleolus  to  theothercomponents  of  the  nucleus 
is  highly  suggestive,  and  seems  to  support  the  view  of  those 
who  hold  that  its  function  is  largely,  at  any  rate,  nutritive. 

In  the  embryonic  tissue  situated  at  the  growing  points 
of  plants,  the  cells  are  all  much  alike,  differentiation  and 
specialisation  only  taking  place  behind  these  regions. 
Consequently  it  is  possible  to  trace  the  changes  which  a 
cell  exhibits  during  its  transition  from  a  primitive  state  to 
its  adult  form,  and  often,  further,  through  the  various  stages 


RECENT  ADVANCES  IN  VEGETABLE  CYTOLOGY.  33 

of  senescence  and  death.  Some  cells,  indeed,  are  not  really 
useful  to  the  plant  of  which  they  form  a  part,  until  they  are 
dead,  i.e.,  till  the  wall  of  the  cell  alone  remains,  whilst  from 
its  cavity  the  protoplasm  has  disappeared. 

The  researches  of  Zacharias  and  of  Rosen,  which  have 
recently  been  published,  were  directed  especially  to  the 
behaviour  of  nuclei  in  the  apical  regions  of  plants,  and 
their  results  in  the  main  are  confirmatory  of  each  other, 
though  the  two  observers  were  interested  in  rather  different 
aspects  of  the  same  problem.  The  nuclei  of  all  actively 
dividing  cells  are  markedly  cyanophil,  and  this  character  is 
especially  noticeable  just  below  the  active  generative  cells. 
At  first  sight  it  may  seem  remarkable  that  in  a  fern  root 
the  nucleus  of  the  large  apical  cell  is  less  cyanophil  than 
are  the  nuclei  of  the  dividing  segment  cells  which  have 
been  cut  off  from  it.  But  the  anomaly  is  only  apparent, 
for  though  all  the  cells  in  the  root  owe  their  origin  ulti- 
mately to  the  division  of  the  apical  cell,  it  must  not  be 
forgotten  that  the  nuclear  divisions  in  the  segments  which 
are  cut  off  from  it  are  far  more  frequent.  The  segments 
divide  up  into  a  very  large  number  of  cells  before  they 
finally  form  permanent  tissue  cells,  and  therefore  it  is  not 
surprising  to  find  that  the  nucleus  of  the  apical  cell,  which 
is  the  ancestor  of  them  all,  contains  less  nuclein  than  the 
more  actively  dividing  descendants.  But  there  are  several 
other  significant  observations  which  go  to  show  that  in  cells 
which  are  in  a  state  capable  of  further  division,  this  faculty  is 
correlated  with  the  presence  of  nuclein  in  their  nuclei.  Rosen 
found  in  the  roots  of  the  bean  and  other  flowering  plants 
that  after  the  tissues  were  beginning  to  show  differentiation, 
the  zone  of  cells  forming  the  pericycle1  retained,  in  their 
nuclei,  the  characters  of  embryonic  cells,  that  is  to  say, 
that,  whereas  the  nuclei  of  the  rest  were  losing  their  cyano- 
phil character  and  were  becoming  erythrophil,  the  pericyclic 
•nuclei  retained  their  nuclein  contents.  .  Now  the  lateral 
roots  arise  in  this  pericyclic  layer,  and  they  do  so  by  the 
differentiation  in   it  of  new  growing  points.      Hence   these 

1  A  zone  of  parenchymatous  cells  sheathing  the  more  central  wood  and 
bast  parts  of  the  vascular  strand. 

3 


34  SCIENCE  PROGRESS. 

new  rootlets  can  only  be  developed  from  cells  which  still 
retain,  or  can  re-awaken,  embryonic  characteristics.  Be- 
hind the  region  in  which  lateral  roots  arise,  the  cells  of 
the  pericycle  lose  their  cyanophil  nature,  and  here  again 
the  loss  is  first  apparent  in  those  cells  from  which,  even 
normally,  no  roots  would  originate,  viz.,  those  situated 
opposite  the  phloem.  It  would  be  interesting  to  know 
whether  in  the  case  of  those  roots  in  which  the  lateral 
rootlets  arise  right  and  left  of  the  protoxylem  (e.g.,  Cruci- 
ferse)  a  corresponding  difference  obtains. 

Again,  Zacharias  noticed  that  during  the  development 
of  the  guard-cells  of  the  stomata  in  a  number  of  leaves 
a  similar  difference  held  good.  In  a  simple  case,  e.g., 
many  Liliacese,  the  mother-cell  of  the  guard-cells  is  cut 
off  from  a  cell  which  is  destined  at  once  to  form  one  of  the 
ordinary  and  relatively  large  epidermal  cells.  In  this  case, 
whilst  the  nucleus  of  the  mother-cell  of  the  stoma  retains 
its  nuclein  contents,  the  other  one  rapidly  becomes  poorer 
in  this  constituent,  it  grows  and  develops  a  large  nucleolus. 
The  small  mother-cell  again  divides  to  form  the  guard-cells 
of  the  stoma,  and  only  then  does  a  nucleolus  become  at  all 
conspicuous,  and  the  nuclein  diminish  in  quantity.  And 
therewith  the  further  capacity  for  division  ceases. 

Besides  the  connection  which  is  shown  to  exist  between 
a  nucleus  which  is  capable  of  division,  and  its  richness  in 
nuclein,  there  are  certain  other  facts  of  importance  which 
demand  notice.  The  nuclei  of  cells  which  are  actively 
dividing  are  commonly  characterised  by  the  possession  of 
smaller  nucleoli  than  are  those  in  which  no  further  divisions 
will  take  place,  but  which  are  still  growing  in  size.  In  fact 
Zacharias  states  generally  that,  as  regards  nuclei  of  cells 
emerging  from  the  meristem  region,  the  nucleoli  first 
increase  to  a  maximum,  that  this  is  accompanied  by  an 
enlargement  of  the  nucleus  as  a  whole,  which  however  only 
reaches  its  maximum  size  after  the  nucleolus  has  done  so, 
and  that  the  latter  body  then  diminishes  faster  than  does 
the  nucleus  as  a  whole. 

Further,  Zacharias  found  that  not  only  is  the  nucleolus 
losing   substance  in   those   cells   which   are   specialising   to 


RECENT  ADVANCES  IN  VEGETABLE  CYTOLOGY.  35 

form  tracheids,  vessels  and  sieve  tubes,  but  that  the  nucleus 
as  a  whole  is  losing,  and  still  more  rapidly,  those  substances 
which  are  capable  of  being  removed   by  peptic  digestion 
from  the  cell.      The  facts  seem  to  suggest  that  it  is  albumin, 
or   some   other   proteid,    which   is   disappearing  ;  and   it   is 
clear  that  the  loss  is  due  to  a  change  in  the  nucleus  itself, 
irrespective    of  the    amount   of  nutrition   available   in   the 
surrounding  plasma,  since  the  change  is  extremely  obvious 
in    the    degenerating    nuclei    of    sieve    tubes,    in  spite    of 
the  fact  that  they  are  surrounded  by  abundant  albuminous 
substances  in  the  slimy  contents  of  the  cells.     On  the  other 
hand,  in  those  cells  which  are  growing  in  size,  preparatory 
to    further  divisions,   such    as   in    spore-mother-cells,     the 
increase    in    albuminous    substances,    both    in    the    nucleus 
generally,  and  especially  in  the  nucleolus,  is  strongly  marked. 
Spore-mother-cells,  as  a  rule,  pass  through  a  relatively  long 
period   of  growth,  and   hence  we  might  perhaps  anticipate 
(as  we  find  to  be  the  case)  that  they  exaggerate  the  changes 
seen  in  the  dividing  and  growing  cells  of  the  apical  meri- 
stem.      But  I  do  not  wish  to  lay  too  much  stress  on  this, 
because  we  know  that  other,  and  profound,  changes  occur 
during  the  growth  of  spore-mother-cells,  and  it  is  uncertain 
to  what  extent  the  facts  just  mentioned  may  be  connected 
with  them. 

It  may  possibly  be  objected  that  observations  like  those 
of  Zacharias  are  open  to  adverse  criticism  on  the  ground  that 
the  chemistry,  and  a  fortiori  the  microchemistry,  of  the 
proteids  and  other  substances  which  occur  in  cells  is  as  yet 
in  such  an  unsatisfactory  condition.  But  this  objection  is 
really  not  a  legitimate  one.  We  know  that  certain  struc- 
tures in  the  cell  are  differentiated  by  their  selective  action 
on  certain  dyes,  and  it  is  to  this  fact  that  their  recognition 
was  due  in  the  first  instance.  But  we  find  the  action  of 
certain  solvents  to  yield  no  less  definite  results.  Given  a 
nucleus  in  a  particular  condition  (as  judged  by  the  structure 
rendered  visible  by  staining),  and  it  will  be  found  that  the 
degree  of  solubility  of  its  constituent  substances  is  charac- 
teristic for  the  particular  stage  in  the  life  history  of  the  cell 
or  of  the  nucleus  which  may  happen  to  have  been  selected. 


36  SCIENCE  PROGRESS. 

Hence  it  seems  clear  that  the  two  methods  ought  both  to 
be  employed  ;  for  whilst  the  staining  exhibits  more  or  less 
completely  the  structural  arrangement  of  the  substances 
present,  the  microchemical  method  not  only  indicates  some 
at  least  of  the  important  differences  which  exist  between 
the  different  structures  revealed  by  the  action  of  staining, 
but  it  teaches  us  that  certain  of  these  same  structures  are  by 
no  means  so  homogeneous  in  their  nature  as  one  might  be 
led  to  suppose  relying  on  the  evidence  derived  from  stain- 
ing alone. 

But  those  who  pin  their  faith  on  stains  sometimes  seem 
to  forget  that  they  are  after  all  only  employing  a  sort  of 
microchemical  method  themselves.  For  the  fact  that 
different  histological  elements  of  the  cell  are  distinguishable 
by  stais,  implies  the  existence  of  a  chemical  dissimilarity 
between  them.  And  this  becomes  the  more  obvious  when, 
owing  to  periodically  recurring  changes  in  the  cell,  we 
assert  that  this  or  that  structure  is  growing  or  diminishing. 
The  investigator  who  is  consciously  proceeding  on  micro- 
chemical lines  is  at  least  not  so  open  to  the  charge  of  mere 
empiricism  as  are  those  who  look  for  salvation  to 
haematoxylin  or  the  anilin  dyes.  He  may  be  wrong  in 
supposing,  for  example,  that  the  phosphorus  within  the 
nucleus  only  occurs  in  the  nuclein,  just  as  he  may  be  in 
error  in  assuming  that  the  substance  nuclein  itself  really  re- 
presents a  chemical  substance  in  the  same  way  that  sugar 
does.  But  he  materially  advances  our  knowledge  of  the 
cell  when  he  determines  the  fact  that  a  body  which  fluctuates 
in  size  as  does  the  nucleolus,  is  composed  of  two  substances 
or  groups  of  substances  one  of  which  is  soluble  in  gastric 
juice  whilst  the  other  is  not  ;  and  that  further,  the  relative 
size  is,  in  the  first  instance,  correlated  with  the  amount  of 
substance  which  the  fermentative  action  of  pepsin  can  render 
soluble. 

It  is  readily  conceded  that  the  bodies  we  call  nuclein, 
plastin,  and  the  like,  possibly  may  not,  as  stated  already, 
represent  chemical  molecules  at  all.  This  does  not,  how- 
ever, diminish  the  interest  attaching  to  the  proof  that  this 
or  that  substance  is  at  one  time  present,  while  at  another 


RECENT  ADVANCES  IN  VEGETABLE  CYTOLOGY.  ^ 

time  it  can  be  no  longer  recognised  in  its  former  place. 
Nor  does  this  observation  lose  in  importance  when  the 
differences  are  shown  to  closely  accompany  changes  in  the 
general  characters  of  the  cells  themselves. 

BIBLIOGRAPHY. 

(i)  WAGER,  H.     Preliminary  Note  on  the  Structure  of  Bacterial 
Cells.     Annals  of  Botany,  vol.  ix. 

(2)  Von    Sachs.      Physiol.    Notizen    II.      Flora,    1892.      Also 

Physiol.  Notizen  IX.     Flora,  Erganzungs  bd.,  1895. 

(3)  STRASBURGER.       Ueber  d.   Wirkungssphare  d.  Kerne  u.   d. 

Zellgrosse.     Histologische  Beitrdge,  v.,  1893. 
(3«)  STRASBURGER.  Schwarmsporenjgameten.Pflanzlichen  sperm- 
atozoiden,  und  das  Wesen  d.  Befruchtung.     Hist.  Beitr.,  iv., 
1892. 

(4)  Boulenger,  G.  A.     On  the  Scaling  on  the  Reproduced  Tail 

in  Lizards.     Proc.  Zool.  Soc,  1888. 

(5)  HABERLANDT,   G.       Ueb.  d.  Beziehungen  Zwischen  Function 

u.  Lage  d.  Zellkerns  b.  d.  Pflanzen.     Jena,  1887. 

(6)  KORSCHELT.     Beitrager  2.     Morph.  u.  Physiol,  d.  Zellkerns. 

Zool.  Jahrb.,  1889. 

(7)  BOVERI.    Ein  Geschlechtlich  erzeugter  Organismus  ohne  Mtit- 

terliche  Eigenschaften.      Sitzungsber.  d.  Gesellsch.  f.  Morph. 
u.  Physiol,  zu  Miinchen,  1889. 

(8)  ZACHARIAS,  E.     Ueb.  d.  Verhalten  d.  Zellkerns  in  Wachsenden 

Zellen.     Flora,  Erganzungs  bd.,  1895. 

(9)  AUERBACH,  L.    Zu  Kentniss  d.  Thier.  Zellen.    Sitzungsber.  d. 

Kgl.  Preuss.  Akad.  d.  Wissensch.,  26th  June,  1890. 
(10)  ROSEN,  F.     Ueb.  tinctionelle  unterschied  verschied.  Kernbes- 

tandtheile  u.  d.  sexualkerne.     Colitis  Beitr.  z.  Biol.  d.  Pflanzen, 

v.,  1892. 
(iOtf)  ROSEN,  F.      Beitr.    z.    Kentniss  d.   Pflanzenzellen.      Colitis 

Beitr.,  vii.,  1895. 

J.   Bretland  Farmer. 


THE  MORPHOLOGY  OF  THE  MOLLUSCA. 

^>  H  E  recent  publication  of  a  number  of  new  manuals  and 
monographs  dealing  with  the  Mollusca  offers  a  favour- 
able opportunity  for  a  review  of  our  knowledge  of  this 
great  phylum  of  the  animal  kingdom.  It  is  not  fifteen 
years  since  Professor  Lankester's  classical  article  on  Mollusca 
was  published  in  the  Encyclopedia  Britannica,  yet  the  con- 
tributions to  Molluscan  morphology  since  that  date  have 
been  not  only  numerous,  but  in  many  cases  of  prime  im- 
portance. 

The  older  method  of  inquiry,  that  of  the  comparison  of 
types  more  or  less  arbitrarily  selected  from  different  groups, 
has  been  succeeded  by  investigations  more  directly  in- 
fluenced by  the  idea  of  evolution.  The  comparison  of  types 
has  been  replaced  by  the  study  of  groups.  The  founda- 
tions of  the  morphological  edifice  were  laid  upon  the  former 
method  ;  the  superstructure  and  details  are  the  result  of 
the  latter.  Homologies  having  been  to  a  large  extent 
determined,  we  now  seek  phylogenies.  It  happens  also 
from  time  to  time  that  the  detailed  study  of  a  group  with 
the  object  of  reconstructing  the  phylogeny  of  its  members 
leads  occasionally  to  the  discovery  that  homologies  based 
on  the  simple  method  of  anatomical  comparison  turn  out 
to  be  nothing  more  than  analogies — recurrent  examples  of 
similar  modifications. 

One  result  of  these  phylogenetic  inquiries  has  been  the 
concentration  of  particular  attention  upon  forms  which  are 
presumably  the  most  primitive  in  each  group  ;  and  great 
advances  have  thus  been  made  in  our  knowledge.  Kow- 
alewsky  and  Marion,  Pruvot,  Wiren,  and  Thiele  have 
enormously  extended  our  acquaintance  with  the  Apla- 
cophorous  Isopleura  ;  primitive  Prosobranchs  (Docoglossa 
and  Rhipidoglossa)  have  been  thoroughly  investigated  by 
Haller  and  Boutan  ;  Bouvier  has  thrown  new  light  upon  the 
Opisthobranchia  by  his  researches  on  Actceon  ;  Boas  and 
Pelseneer  have  revolutionised  our  ideas   of  the  Pteropoda 


THE  MORPHOLOGY  OF  THE  MOLLUSC  A,  39 

by  their  work  upon  Limacina  among  the  Thecosomata,  and 
upon  Dexiobranchcea  and  other  types  among  the  Gymnoso- 
mata  ;  the  morphology  of  the  Pelecypoda  has  been  further 
elucidated  by  Pelseneer's  observations  upon  Nucula  and 
other  primitive  forms,  and  important  contributions  to  our 
knowledge  of  the  Cephalopoda  were  made  during  the  past 
year  by  Huxley  and  Pelseneer  in  the  case  of  Spirilla,  that 
last  survivor  of  the  ancient  types  of  Decapod  Dibranchiates. 
We  doubt  if  any  equivalent  group  of  the  animal  kingdom, 
except  perhaps  the  Echinoderma,  has  been  the  subject  of 
such  productive  researches  as  the  M ollusca  during  the  period 
under  consideration  ;  and  certainly  the  phylogenetic  method 
of  inquiry  has  attained  no  greater  triumphs  than  in  the 
hands  of  Bouvier,  Haller,  Pelseneer,  and  other  inves- 
tigators of  the  Gastropod  and  Lamellibranch  series. 

In  the  present  article  I  propose  to  deal  more  especially 
with  recent  contributions  to  our  knowledge  of  the  Molluscan 
nervous  system,  reserving  a  fuller  consideration  of  other 
questions  for  a  later  article. 

There  is  one  writer,  however,  whose  views  must  first  of 
all  be  dealt  with,  as  on  a  great  number  of  fundamental 
points  they  are  opposed  to  all  current  conceptions  of 
Molluscan  morphology.  These  views  merit  some  detailed 
consideration,  moreover,  for  they  are  based  on  propositions 
which  are  not  without  a  certain  appearance  of  plausibility, 
and  may  well  serve  as  test-questions  by  which  to  examine 
into  the  accuracv  of  the  homologies  which  have  been 
generally  admitted  to  exist  between  the  different  sections 
of  the  Molluscan  phylum. 

Thiele  has  published  his  views  in  a  series  of  lengthy 
papers,  the  references  to  which  will  be  found  in  the  biblio- 
graphy (23,  24,  25).  He  regards  the  Mollusca  and  Anne- 
lida as  direct  descendants  of  Polyclad  Turbellarians,  and 
his  identifications  of  homologous  organs  in  the  different 
Molluscan  groups  are  determined,  not  by  a  direct  comparison 
of  the  organisation  of  these  types  one  with  another,  but 
by  independent  comparisons  of  the  organisation  of  the 
different  Molluscan  types  with  that  of  sucker-bearing 
Polyclads.      The  group    Mollusca  is  thus  made  to  lose  its 


40  SCIENCE  PROGRESS. 

compactness,  and  characteristic  organs,  such  as  mantle  and 
ctenidium,  which  have  been  regarded  as  homologous 
throughout  the  Molluscan  series,  are  interpreted  in  different 
ways  in  the  different  types,  as  the  exigencies  of  Thiele's 
theory  demand.  One  of  the  first  propositions  assumed  by 
this  writer  is  that  the  foot  of  the  Mollusca  is  simply  a  colossal 
enlargementof  the  ventral  sucker  of  the  Polyclad;  thesuctorial 
function  of  the  foot  in  Chiton  and  the  lower  Gastropoda  is 
pointed  to  in  support  of  this  comparison.  A  series  of 
more  revolutionary  propositions  is  then  promulgated  in 
consequence  of  the  necessity  under  which  the  author  is 
placed  of  discovering  the  primitive  body-edge  of  the 
Mollusca  comparable  to  the  edge  of  the  body  of  the  Tur- 
bellaria.  This  primitive  body-edge  Thiele  identifies  by 
means  of  the  lateral  sense-organs  which  characterise  the 
epipodium  in  the  Rhipidoglossa  and  the  margin  of  the 
mantle  in  Pelecypoda.  The  epipodium  in  Gastropoda  and 
the  mantle  edge  in  Pelecypoda  are  thus  taken  by  this  writer 
to  represent  the  sides  or  edge  of  the  body  in  the  Tur- 
bellarian  ancestor.  The  epipodium  in  Gastropoda  and  the 
mantle  edge  in  Pelecypoda  consequently  separate  the 
dorsal  from  the  ventral  regions  of  the  body  in  those  groups. 
It  follows  from  this  that  the  ctenidia  of  Gastropoda,  which 
are  supra-epipodial  in  position,  are  not  homologous  with 
the  ctenidia  of  Pelecypoda,  which  are  infra-pallial.  How  we 
are  to  regard  the  anus,  which  is  dorsal  in  the  one  group  and 
ventral  in  the  other,  is  not  explained.  But  since  in  oper- 
culate  Rhipidoglossa  the  operculum,  like  the  shell,  is 
situated  above  the  epipodium,  we  are  told  that  the  oper- 
culum must  also  be  regarded  as  dorsal  in  position,  as  well 
as  serially  homologous  with  the  shell  proper.  This,  in 
Thiele's  eyes,  compares  well  with  the  condition  of  affairs  in 
Chiton,  whose  shelly  plates  are  without  doubt  serially 
homologous.  Moreover,  although  the  existence  of  an 
epipodium  in  Chiton  has  not  been  hitherto  recognised, 
Thiele  argues  that,  since  the  pallial  fold  in  this  form  re- 
presents the  primitive  body-edge,  it  must  also,  together  with 
the  series  of  ctenidia  which  are  attached  to  its  lower  surface, 
be   regarded   as  the    homologue    of  the  epipodium    of  the 


THE  MORPHOLOGY  OF  THE  MOLLUSC  A.  41 

Rhipidoglossa.  The  ctenidia  of  Chiton  are,  in  fact,  re- 
garded as  modified  epipodial  cirri.  The  consequence  of 
this  view  is  that  while  the  mantle  of  Chiton  and  the  mantle 
of  Pelecypoda  are  regarded  as  homologous,  the  mantle  of 
the  Gastropoda  is  supposed  to  represent  only  a  portion  of 
the  mantle  in  these  other  forms,  and  its  projecting  rim, 
similar  as  it  appears  to  be  in  the  two  cases,  is  held  to  be  a 
new  and  secondary  formation  unrepresented  in  the  Am- 
phineura  and  Pelecypoda. 

Nowhere,  however,  do  we  find  in  Thiele's  voluminous 
writings  any  explanation  of  the  anomaly  which  ought  to 
have  occurred  to  him,  that  while  in  Chiton  the  anus  is 
"ventral,"  and  lies  well  beneath  the  "epipodium"  and  the 
last  shell-plate,  in  operculate  Gastropods  the  intestine  opens 
not  only  above  the  epipodium,  but  between  the  operculum 
and  the  shell  of  the  embryo — a  relation  which  could  only  be 
represented  in  Chiton,  if  Thiele's  theories  were  correct,  by 
the  situation  of  the  anus  between  two  of  the  shell-plates 
upon  the  back  of  that  animal  ! 

The  nervous  system  of  the  Mollusca  is  treated  by  Thiele 
with  a  ruthlessness  no  less  than  that  which  is  meted  out 
to  the  external  organs  of  the  body.  Let  us  take  the 
Amphineura  first.  In  this  group,  if  the  relations  of  the 
nervous  system  in  Chiton  be  taken  as  typical,  we  have 
dorsal  to  the  gut  a  great  ganglionic  nerve-ring  whose  lateral 
components  are  usually  referred  to  as  the  lateral  or  pleuro- 
visceral  cords.  Connected  anteriorly  with  the  cerebral 
enlargements  of  this  nerve-ring  is  a  pair  of  ventral  or  pedal 
cords,  connected  with  one  another  by  a  series  of  commis- 
sures lying  beneath  the  gut,  and  also  with  the  lateral  cords 
by  means  of  lateral  connectives.  The  lateral  cords  inner- 
vate the  pallial  sense-organs,  gills,  and  viscera  ;  the  ventral 
cords  the  musculature  of  the  foot.  The  lateral  cords  are 
regarded  by  Thiele  as  the  homologues  of  the  lateral  cords 
or  nerve-ring  of  the  Turbellarians.  and  the  ventral  cords  are 
taken  to  correspond  to  the  ventral  longitudinal  nerves  of 
the  same  forms.  So  far  we  find  nothing  either  erratic  or 
original,  for  the  same  view  has  already  been  taken  by  Lang 

(16). 


42  SCIENCE  PROGRESS. 

But  the  novelties  begin  with  Thiele's  interpretations  of 
the  nervous  system  of  Gastropoda  and  Pelecypoda.  We 
have  already  pointed  out  Thiele's  view  that  the  epipodium 
of  Gastropods  represents  the  primitive  body-edge.  Now 
at  the  base  of  the  epipodium  in  Fissurella  and  Haliotis  there 
lies  a  ganglionic  plexus  ;  and  this  plexus,  which  takes  the 
form  of  an  incomplete  ring,  is  regarded  as  the  homologue 
of  the  lateral  cords  of  Turbellarians  and  Amphineura.  The 
series  of  epipodial  nerves  which  connect  the  epipodial  plexus 
with  the  upper  half  of  the  pedal  cords  in  Rhipidoglossa  is 
compared  with  the  series  of  connectives  between  the  lateral 
and  ventral  cords  in  Amphineura. 

This  seems  very  plausible  until  one  recollects  (i)  that, 
the  epipodium  being  infra-rectal,  the  epipodial  plexus  is 
also  infra-rectal  and  thus  difficult  to  compare  with  the 
lateral  cords  of  Amphineura,  whose  "commissure"  is  supra- 
rectal  ;  and  (2)  that,  whereas  in  Amphineura  the  lateral 
cords  innervate  practically  the  whole  of  the  pallium  and 
viscera,  in  Rhipidoglossa  the  epipodial  plexus  has  nothing 
to  do  with  any  other  organs  except  the  sense-organs  of  the 
epipodium.  If  the  pallium  of  the  Gastropoda  is  really,  as 
Thiele  maintains,  a  secondary  differentiation  of  the  primary 
pallium  of  the  Amphineura,  one  would  expect  that  its 
innervation  would  also  be  effected  by  progressive  differen- 
tiation of  the  nerve-centres  which  supplied  the  primary 
pallium,  viz.,  from  the  lateral  or  epipodial  centres.  So  far 
from  this  being  the  case,  however,  Thiele  himself  (xxv.,  pp. 
587-9)  adopts  the  view  that  the  pallial  nerves  as  well  as  the 
pleural  ganglia  of  Gastropoda  are  secondary  derivatives  of 
the  ventral  or  pedal  cords. 

The  recklessness  of  Thiele's  comparisons  reaches  its 
high-water  mark,  perhaps,  in  his  remarks  on  the  nervous 
system  of  Pelecypoda.  Correlated  with  the  existence  of 
numerous  sense-organs  (eyes,  tentacles,  etc.)  along  the 
mantle  edge,  there  exists  in  many  forms  {Area,  Pecten, 
Pinna,  etc.)  a  nervous  ring  around  the  mantle  which  may 
take  the  form  either  of  a  complete  ring  of  peripheral  ganglia 
united  by  a  plexus,  or  of  a  circumpallial  ganglionated  nerve, 
as  was  recognised  by  Duvernoy  (5)  more  than  thirty  years 


THE  MORPHOLOGY  OF  THE  MOLLUSC  A.  43 

ago.  Since  the  mantle-lappets  of  the  two  sides  of  the  body 
unite  posteriorly  above  the  anus,  this  pallial  nerve-ring  lies 
above  the  gut.  The  ring  is  connected  with  the  cerebro- 
pleural  ganglia  by  means  of  the  anterior  pallial  nerves,  and 
with  the  visceral  (parieto-splanchnic)  by  means  of  branches 
from  the  great  posterior  pallial  nerves.  Accordingly  Thiele 
homologises  the  circumpallial  nerve-ring  with  the  lateral 
cords  of  Chiton  and  with  the  epipodial  plexus  of  the  Rhi- 
pidoglossa. 

The  first  of  these  homologies  seems  not  unreasonable,  for 
no  one  disputes  the  homology  between  the  mantle  of  Chiton 
and  that  of  Pelecypoda.  Moreover  Kowalevsky's  discovery 
that  Chiton  in  its  later  embryonic  phases  is  provided  with 
a  pair  of  transitory  eyes  which  lie  outside  the  velar  area 
and  have  some  close  connection  with  the  lateral  nerve- 
cords,  renders  this  comparison  particularly  worthy  of 
attention.  But  how  the  circumpallial  nerve  of  Pelecypoda 
can  be  in  any  sense  homologous  with  the  epipodial  plexus 
of  Gastropoda,  when  the  latter  structure  lies  beneath  the 
gut  and  has  no  connection  with  the  cerebral  ganglia,  either 
directly  or  by  the  intermediation  of  the  pleural  ganglia,  it 
is  altogether  impossible  to  conceive.  And  this  is  not  all. 
The  posterior  connection  between  the  circumpallial  nerve 
of  Pelecypoda  and  the  visceral  ganglia  is  compared  by 
Thiele  with  the  posterior  connectives  between  the  lateral 
and  ventral  cords  of  Amphineura  ;  and  the  time-honoured 
visceral  nerve-cords  of  Pelecypoda,  with  the  visceral  (parieto- 
splanchnic)  ganglia  upon  them,  are  homologised  with  the 
ventral  cords  of  the  Amphineura.  To  reveal  the  absurdity 
of  these  comparisons  it  is  sufficient,  I  think,  to  remind  my 
readers  that  the  ventral  cords  of  Chiton  are  concerned  ex- 
clusively with  the  innervation  of  the  musculature  of  the 
foot  ;  while  the  visceral  cords  of  Pelecypoda  innervate 
the  body-wall,  ctenidia  and  viscera^  in  addition  to  the 
posterior  adductor  muscle.  How  these  supposed  homo- 
logues  of  the  ventral  cords  of  Chiton  have  come  to  assume 
so  many  of  the  functions  of  the  lateral  or  pallio-visceral 
cords,  is  not  explained  ;  and  since  Pelecypoda  possess  a 
pair  of  pedal  ganglia  in  the  foot,  as  typical  in  their  relations 


44  SCIENCE  PROGRESS. 

as  those  of  any  Gastropod — in  Nucula  to  the  extent  even 
of  having  separate  cerebro-pedal  and  pleuro-pedal  connec- 
tives (18,  19)  —  it  seems  profitless  to  pursue  these  ill- 
balanced  speculations  any  further. 

The  utmost  ingenuity  cannot  overcome  the  fact  that 
there  is  a  fundamental  disparity  between  the  Turbellarian 
and  Molluscan  body.  This  disparity  is  revealed  by  em- 
bryology ;  but  to  embryology  Thiele  pays  scant  attention. 
Thiele's  argument  is  practically  this  (24,  p.  504), — that 
the  only  route  from  Ccelenterates  to  Bilateralia  is  via  the 
Ctenophores  to  Polyclads,  and  that  Annelids  and  Molluscs 
are  consequently  to  be  derived  from  Polyclad  ancestors. 
Embryology  seems  to  me,  however,  to  point  to  two  lines  of 
descent  at  least,  from  the  Ccelenterates  to  the  Bilateralia. 
In  each  case  the  oral  surface  of  the  Ccelenterate  ancestor 
became  the  ventral  surface  of  the  Bilateral  descendant  ;  but 
along  one  line  of  descent  the  primitive  mouth  or  blastopore 
retained  its  ancestral  form  as  a  simple  circular  orifice  in  the 
middle  of  the  ventral  surface,  and  opened  into  a  gastral 
cavity  devoid  of  an  anal  orifice  (Polyclads)  ;  while  along  the 
line  of  descent  which  led  to  the  Annelida  and  Mollusca  the 
blastopore  elongated  along  the  ventral  surface,  as  Sedg- 
wick has  so  ably  contended,  its  lips  coalesced  except  at  the 
two  extremities,  and  these  open  ends  constituted  the  mouth 
and  anus  of  the  Ccelomate  descendants.  Thiele  has 
altogether  overlooked  the  significant  behaviour  of  the  blas- 
topore in  Annelidan  and  Molluscan  embryos  ;  and  since 
no  similar  modification  of  the  blastopore  is  known  in  the 
case  of  Turbellarians  and  Trematodes,  in  which  groups  the 
absence  of  an  anus  is  so  marked  a  characteristic,  we  are 
amply  warranted,  I  think,  in  drawing  the  conclusions  which 
I  have  emphasised  above. 

The  admission  of  this  distinction  is  however  fatal  to 
any  theory  of  the  Polyclad  ancestry  of  the  Mollusca.  The 
foot  of  the  Mollusca  is  a  development  of  the  fused  lips  of 
the  elongated  blastopore,  and  can  in  no  case  be  homo- 
logised  with  the  ventral  sucker  of  Turbellarians  which  lies 
entirely  behind  the  blastopore.  The  same  remark  applies 
to  Lang's  comparison  of  the  Molluscan  foot  with  the  ventral 


THE  MORPHOLOGY  OF  THE  MOLLUSC  A.  45 

surface  of  the  Turbellarian.  The  foot  is  undoubtedly  part 
of  the  ventral  surface  of  the  Mollusc,  and  as  such  may  be 
compared,  in  a  general  way,  with  the  creeping  surface  of  a 
Planarian  ;  but  as  a  specialised  organ,  developed  from  the 
fused  lateral  margins  of  a  slit-like  blastopore,  it  has  no 
homoloeue  in  the  organisation  of  the  Turbellaria. 

Let  us  now  see  what  light  has  been  thrown  on  the 
problems  of  Molluscan  morphology  by  the  researches  of 
other  investigators. 

The  visceral  commissure. — One  of  the  greatest  dif- 
ficulties in  comparing  the  Amphineura  with  the  Gastropoda 
or  other  Molluscan  types  has  long  been  the  fact  that  the 
lateral  or  pleuro-visceral  cords  of  Chiton,  which  innervate 
the  gills,  viscera,  and  mantle,  are  united  to  one  another 
posteriorly  by  a  "commissure"  lying  above  the  rectum; 
whereas  the  visceral  commissure  of  Gastropoda  and  Pelecy- 
poda,  etc.,  lies  below  the  intestine. 

A  little  care  in  the  use  of  words  would  have  prevented 
much  of  the  confusion  and  controversy  which  has  arisen  on 
this  subject  of  the  position  of  the  visceral  commissure. 
Words,  as  Bacon  phrases  it,  put  constraint  upon  the  in- 
tellect, and  there  is  no  doubt  that  the  disagreement  and 
perplexity  of  naturalists  concerning  this  point  have  been 
caused  by  one  of  the  idola  fori  which  they  have  themselves 
set  up,  rather  than  by  any  intrinsic  incompatibility  in  the 
facts  themselves.  If  the  language  must  still  be  maintained, 
I  must  at  least  point  out  that  there  are  commissures  and 
commissures,  and  that  one  may  be  a  commissure  in  fact, 
and  another  only  in  name.  The  suprarectal  ''commissure" 
in  Amphineura  is  ganglionic,  and,  like  the  rest  of  the 
pleuro-visceral  nerve-ring,  is  formed  in  situ  by  delamination 
from  the  ectoderm  (15).  It  is  not  a  commissure  in  the 
strict  sense  of  the  word,  but  an  integral  portion  of  an 
annular  central  nervous  system.  But  the  visceral  loop  of 
other  Molluscs  consists  merely  of  nerve-fibres  connecting 
usually  a  couple  of  visceral  ganglia  with  one  another,  and 
with  the  pleural  ganglia.  Now  nerve-fibres  are  outgrowths 
from  nerve-cells,  and  if  two  groups  of  nerve-cells  should 
happen  to  take  a  somewhat  deep-seated  position  in  the  body 


46  SCIENCE  PROGRESS. 

before  their  fibres  have  grown  out  (which  is  not  a  rare 
embryological  phenomenon),  there  should  be  nothing  in- 
comprehensible in  their  fibres  taking  the  shortest  route  and 
meeting  beneath  the  gut  instead  of  over  it.  Clearly,  there- 
fore, the  ventral  position  of  the  visceral  commissure  in 
most  Mollusca  by  no  means  precludes  the  possibility  of  the 
essential  homology  between  the  visceral  loop  of  these 
forms  and  part  of  the  pleuro-visceral  ring  of  Amphineura. 

The  other  differences  between  the  visceral  loop  of  most 
Mollusca  and  the  pleuro-visceral  ring  of  Amphineura  are- 
principally  differences  in  the  degree  of  segregation  and 
concentration  of  ganglion-cells  and  nerve-fibres.  The 
pleuro-visceral  ring  of  Chiton  represents  a  very  primitive 
nervous  system,  characterised  by  the  more  or  less  even 
diffusion  of  ganglion-cells  over  the  whole  length  of  the 
cord,  while  the  nerves  arising  from  it  are  not  united  into 
large  trunks,  but  are  given  off  at  repeated  intervals  in  a 
manner  which  is  almost  metameric.  The  nerves  springing 
from  it  innervate  the  same  parts  of  the  body  as  the  com- 
bined pleural  and  visceral  ganglia  of  Gastropods  and  other 
Molluscs,  viz.,  mantle,  ctenidia,  intestine,  heart,  nephridia, 
and  gonads.  But  if,  after  the  reduction  of  the  ctenidia  to 
a  single  pair,  we  imagine  a  process  of  segregation  to  set  in 
between  these  various  elements,  the  more  strictly  visceral 
centres  would  become  separated  from  the  superficial  pallial 
centres,  and  would  assume  a  deeper  position  in  the  body. 
The  law  of  concentration  would  apply  in  this  as  in  other 
cases  of  evolution  of  nervous  systems  (3),  and  the  result  of 
the  whole  process  would  be  the  differentiation  of  a  visceral 
nervous  system,  consisting  of  ganglia  and  commissural 
fibres,  out  of  the  primitively  mixed  and  diffuse  pleuro-visceral 
system.  If  the  primitive  relations  to  the  gut  and  ring-like 
form  were  retained  at  all,  they  would  be  retained,  not 
necessarily  by  the  visceral  system,  which  has  ex  hypothesi  un- 
dergone considerable  changes,  but  by  the  pallial  (=  pleural) 
system,  which  has  undergone  no  change,  except  possibly 
one  of  incipient  concentration. 

The  position  of  the  commissural  fibres  of  the  visceral 
ganglion  in  relation  to  the  gut  becomes  a  matter  of  sub- 


THE  MORPHOLOGY  OF  THE  MOLLUSC  A.  47 

ordinate  importance  if  the  evolution  of  the  nervous  system 
has  proceeded  upon  these  lines,  as  will  be  made  evident 
later  on.  As  a  matter  of  fact  the  visceral  commissure  is 
situated  below  the  gut — a  relation  which  is  possibly  fore- 
shadowed in  Chiton  by  a  connection  beneath  the  gut  of  the 
two  gastric  nerves  described  by  Haller  (8). 

Pelseneer  (19)  indeed  goes  so  far  as  to  identify  these 
gastric  nerves  of  Chiton  with  the  visceral  commissure  of 
Gastropoda  and  Pelecypoda;  but  the  considerations  which  I 
have  emphasised  above  show  that  the  typical  visceral  nerves 
and  commissure  have  not  yet  arisen  in  the  Amphineura  ; 
they  do  not  arise,  in  fact,  until  the  branchial,  nephridial, 
genital  and  enteric  branches  of  the  primitive  pallio-visceral 
cords  are  all  united  into  one  common  trunk.  There  is 
some  doubt,  moreover,  as  to  the  existence  of  the  gastric 
nerves  described  by  Haller,  since  two  investigators,  Plate 
(20)  and  Thiele,  have  been  unable  to  discover  them  in 
species  of  Chiton  examined  by  themselves. 

A  valuable  contribution  to  this  part  of  the  subject  is 
contained  in  Haller's  recent  Studien  (11).  In  the 
common  cyclobranchiate  types  of  Limpet  the  pallial  nerves 
are  separate  from  one  another  behind,  and  seem  to  be 
mere  outgrowths  of  the  pleural  ganglia  (Bouvier,  3,  p.  19); 
but  in  Lottia,  one  of  the  more  primitive  monobranchiate 
forms,  Haller  shows  that  the  pallial  nerves  of  the  two  sides 
are  directly  continuous  with  one  another  posteriorly,  and  make 
a  complete  arch  round  the  edge  of  the  mantle.  They  are 
moreover  not  mere  nerves,  since  they  consist  of  a  core  of 
fibres  surrounded  by  an  outer  coating — discontinuous,  it  is 
true — of  ganglion-cells.  They  are  clearly  the  posterior 
continuations  of  the  pleural  ganglia,  and  represent  the  re- 
mainder of  the  pallio-visceral  nerve-ring  of  the  Amphineura 
after  the  separation  of  the  visceral  elements.  This  view  is 
further  borne  out  by  the  existence  of  several  connectives 
between  the  pallial  ring  and  the  pedal  cords  in  addition  to 
the  stout  ganglionic  connective  which  in  higher  forms 
becomes  the  persistent  pleuro-pedal  connective. 

The  pleural  ganglion. — Haller's  discovery  recorded  in 
the    preceding  paragraph   shows    clearly   the  error    of   the 


48  SCIENCE  PROGRESS. 

view  by  which  the  pleural  ganglion  is  regarded  as  a 
derivative  of  the  pedal  cords  (Bouvier,  Pelseneer,  etc., 
passim).  This  view  is  founded  on  the  fact  that  in  the  lower 
Gastropoda  (Docoglossa  and  Rhipidoglossa)  the  pleural 
ganglia  are  directly  continuous  with  the  anterior  ends  of 
the  pedal  cords,  while  in  the  higher  types  the  pleural  ganglia 
gradually  move  further  and  further  away  from  the  pedal 
ganglia,  and,  travelling  along  the  cerebro-pleural  connectives, 
eventually  come  into  contiguity  with  the  cerebral  ganglia 
(Tenioglossa)  or  even  fuse  with  them  to  form  a  single 
cerebro-pleural  ganglion  on  each  side  (Pelecypoda). 

The  close  connection  between  the  pleural  and  pedal 
ganglia  in  the  lower  forms  may  now  be  interpreted 
in  a  different  manner.  The  ganglion-cells  which  were 
primitively  distributed  over  the  whole  extent  of  the  pallial 
nerve-ring  have  been  concentrated  at  the  anterior  ex- 
tremities of  its  lateral  portions,  as  Haller's  observations 
on  Lottia  show— or  rather  in  the  reo-ion  of  the  first 
pleuro-pedal  connective,  for  the  most  anterior  portion  of 
the  primitive  pallial  cords  is  represented  by  the  cerebro- 
pleural  connective.  The  shortness  of  the  pleuro- 
pedal  connecting  piece  and  the  great  concentration  of 
ganglion-cells  which  takes  place  at  its  two  extremities 
prevent  any  sharp  demarcation  between  the  pleural  and 
pedal  ganglia  in  these  lower  forms  ;  but  a  comparison  of 
the  nervous  system  of  Lottia  with  that  of  Chiton  (Thiele, 
2 3 ?  P-  387)  leaves  no  room  for  doubt  as  to  the  correct- 
ness of  this  interpretation,  which  throws  a  flood  of  light 
upon  numerous  other  points  which  have  been  difficult  to 
understand  upon  the  older  views.  It  explains,  for  example, 
why  the  cerebro-pleural  and  cerebro-pedal  connectives 
should  be  already  distinct  from  each  other  in  the  lower 
Gastropods  at  a  stage  when  the  pleural  ganglia  are  in 
actual  continuity  with  the  pedal  cords,  and  it  sets  at  rest 
the  controversy  as  to  the  meaning  of  the  lateral  furrow 
in  the  pedal  cords  of  Rhipidoglossa  which  has  been  waged 
with  so  much  skill  in  the  rival  pages  of  the  Archives  de 
Zoologie  and  the  Bulletin  Scientifique  de  la  France  et  de  la 
Belgique. 


THE  MORPHOLOGY  OF  THE  MOLLUSC  A.  49 

Development  of  the  pleural  ganglion. — That  the  pleural 
ganglion  is  essentially  distinct  from  the  pedal  is,  I  think, 
sufficiently  clear  from  the  facts  of  development.  Although 
these  ganglia  are  placed  so  close  together  and  are  so  inti- 
mately connected  in  the  lower  Gastropods  there  is  not  a 
single  case  on  record  in  which  the  pleural  ganglion  has  been 
observed  to  arise  from  the  pedal  ganglion,  or  from  a 
common  pleuro-pedal  rudiment  in  the  embryo.  It  is 
equally  true  on  the  other  hand  that  Sarasin's  derivation  of 
the  cerebral  and  pleural  ganglia  from  a  common  rudiment 
in  Bithynia  (the  cephalic  sense-plate)  has  been  opposed  by 
v.  Erlanger,  who  shows  that  all  the  great  ganglionic  centres 
arise  separately,  and  do  not  become  connected  with  one 
another  until  after  their  differentiation  (7). 

A  renewed  investigation  of  the  origin  of  the  cerebro- 
pleural  ganglion  in  Pelecypoda  would  be  of  great  interest 
in  this  connection.  Pelseneer's  ( 1 8)  observations  on  Nuctila 
have  placed  the  fact  of  the  composite  nature  of  this  ganglion 
in  Pelecypoda  beyond  all  doubt ;  and  still,  to  the  best  of 
my  knowledge,  no  one  has  yet  observed  the  appearance  in 
the  embryo  of  a  pleural  element  distinct  from  the  main  body 
of  the  ganglion.  This  apparent  community  of  origin  of  the 
cerebral  and  pleural  ganglia  in  Pelecypoda  may  be  compared 
with  the  direct  continuity  of  the  cerebral  and  pleural 
elements  of  the  nervous  system  in  Amphineura. 

Development  of  the  visceral  ganglia.  —  Sarasin  en- 
deavoured to  show  that  the  visceral  ganglia  of  Bithynia, 
together  with  the  pedal  and  abdominal  ganglia,  arise  in  the 
embryo  from  a  common  ventral  proliferation  of  the  ectoderm 
which  he  compares  with  the  ventral  ganglionic  chain  of 
Annelida.  On  this  point  also  Sarasin  has  been  corrected 
by  v.  Erlanger,  who  shows  that  all  these  ganglia  arise 
separately  from  one  another  in  Bithynia  (7),  as  well  as  in 
Palndina  (6). 

The  visceral  ganglia  are  also  quite  distinct  from  the 
pleural  ganglia  in  their  origin,  as  v.  E Hanger's  observations 
show.  In  one  important  respect,  however,  the  visceral 
ganglia  and  the  pleural  ganglia  betray  a  marked  similarity, 
the  significance  of  which  seems,   however,  to  have  escaped 

4 


50  SCIENCE  PROGRESS. 

the  attention  of  its  discoverer.  In  Paludina  v.  E danger 
figures  the  pleural  ganglia  arising  from  the  ectoderm  on 
each  side  of  the  body  at  a  point  just  outside  the  velar  area, 
but  in  actual  contiguity  with  the  cells  of  the  ciliated  ring. 
In  Bithynia  (7,  Taf.  xxvi.,  fig.  16)  he  figures  the  same 
condition  of  things  for  the  pair  of  visceral  ganglia.  The 
only  difference  in  origin  between  the  two  ganglia  is  that  the 
visceral  ganglia  arise  behind  the  pleural  ganglia.  If  the 
Molluscan  veliger  possessed  a  nerve-ring  beneath  its  proto- 
troch  (velum),  as  occurs  in  the  trochosphere  of  the  Annelida, 
it  is  quite  clear  that  the  pleural  and  visceral  ganglia  of 
Bithynia  and  Paludina  would  represent  a  series  of  gangli- 
onic thickenings  along  the  course  of  the  nerve-ring.  Apart 
from  this  inference,  however;  the  topographical  relations  to 
which  I  have  called  attention  seem  sufficient  to  establish 
the  proposition  that  the  pleural  and  visceral  ganglia,  and, 
as  I  shall  show  directly,  the  abdominal  ganglion  also,  of 
Gastropods — and,  therefore,  of  other  Mollusca — belong  to 
a  group  of  dorso-lateral  nerve-centres  quite  distinct  from 
that  which  is  represented  by  the  ventral  or  pedal  cords. 
Here  again  we  are  reminded  of  the  direct  continuity  of  the 
pleural  and  visceral  nerve-centres  in  the  Amphineura. 

Development  of  the  abdominal  ganglion. — In  Chiton, 
as  Kowalevsky  has  shown  (15),  the  unpaired  abdominal 
ganglion,  or,  as  it  is  often  called,  the  visceral  ganglion, 
arises  by  a  proliferation  of  the  ectoderm  at  the  hinder  pole 
of  the  embryo,  dorsally  to  the  site  of  the  future  proctodeum. 
In  the  adult  this  ganglion  is  simply  a  special  concentration 
of  ganglion-cells  on  the  supra-anal  portion  of  the  pleuro- 
visceral  ring. 

The  abdominal  ganglion  of  Gastropods  is  also  situated 
at  the  hinder  end  of  the  visceral  loop,  but  lies  of  course 
ventral  to  the  gut.  Can  these  two  ganglia  be  regarded  as 
homologous  ? 

If  Molluscs  were  mere  mechanical  models  the  answer 
would  be  undoubtedly  in  the  negative ;  but  embryology 
points  unhesitatingly  to  the  opposite  conclusion.  Von 
Erlanger  has  shown  that  in  Bithynia  as  well  as  in  Paludina 
the  abdominal   ganglion    develops    as    an    ectodermal   pro- 


THE  MORPHOLOGY  OF  THE  MOLLUSC  A.  51 

liferation  of  the  floor  of  the  mantle-cavity,  i.e.,  that  the 
ganglion  is  essentially  a  dorsal  ganglion.  Its  final  situation 
on  the  course  of  the  sub-intestinal  nerve-loop  is  rendered 
possible  by  the  fact  that  its  connectives  with  the  visceral 
eanolia  are  not  delaminated  from  the  ectoderm,  as  are  the 
ganglionic  pleuro-visceral  cords  of  Chiton,  but  are  mere 
fibrous  outgrowths  from  the  ganglia  themselves.  Embry- 
ology is  thus  in  complete  accord  with  the  views  which  have 
been  maintained  in  the  earlier  part  of  this  paper  as  to  the 
homologies  and  origin  of  the  visceral  nervous  system  in 
Mollusca. 

The  pallial  and  visceral  commissures  in  Cephalopoda. 
— It  has  long  been  known  (Hancock)  that  in  many  Cepha- 
lopoda the  stellate  ganglia  on  the  pallial  nerve-cords  are 
connected  with  one  another  above  the  gut  by  a  transverse 
commissure.  Is  this  commissure  a  relic  of  the  pallio- visceral 
nerve-ring  of  the  Amphineura  and  homologous  with  the 
pallial  ring  of  Lottia,  or  is  it  merely  a  secondary  connection  ? 

In  Spirilla  a  remarkable  arrangement  of  the  pallial 
commissure  has  been  recognised  by  Huxley  and  Pelseneer 
in  their  recent  memoir  (12).  The  commissure  is  not  in 
this  case  a  straight  transverse  band,  but  consists  of  two 
curved  cords  which  arise  from  the  right  and  left  stellate 
ganglia  respectively,  and  at  their  junction  in  the  median 
line  of  the  body  give  off  a  median  pallial  nerve  which  runs 
for  a  short  distance  forwards,  and  then  passing  over  the 
anterior  margin  of  the  shell — which  is,  of  course,  internal — 
becomes  recurrent  and  runs  along  the  part  of  the  mantle 
contained  within  the  last  chamber  of  the  shell.  Pelseneer  is 
thus  led  to  regard  the  commissure  with  its  median  nerve  as 
formed  by  the  two  original  pallial  nerves  fused  together. 
The  connection  between  the  stellate  ganglia  having  thus 
arisen  in  the  primitive  Dibranchiates  (apparently  in  con- 
nection with  the  reduction  in  size  and  enclosure  of  the 
chambered  shell),  higher  forms  show  a  series  of  stages  in 
its  subsequent  degradation,  until  it  is  finally  lost  in  the 
Octopoda.  The  absence  of  a  pallial  commissure  in  Nautilus 
also  supports  Pelseneer's  view  that  in  Cephalopoda  this 
structure  is  not  of  any  primary  importance. 


52  SCIENCE  PROGRESS. 

At  the  same  time  when  Pelseneer  added  a  paragraph  to 
the  effect  that  the  supra-rectal  commissure  of  the  Amphi- 
neura  is  also  a  merely  secondary  junction  of  the  pallial 
nerves,  he  was  probably  not  yet  acquainted  with  Haller's 
work  on  Lottia,  and  allowed  his  views  upon  the  Polychsete 
ancestry  of  the  Mollusca  to  bias  his  interpretation  of  the 
Molluscan  nervous  system. 

In  a  recent  paper  on  the  anatomy  of  Nautilus  Mr. 
Graham  Kerr  (13)  also  refers  to  the  question  of  the  supra- 
rectal  commissure.  It  will  be  remembered  that  in  Nautilus 
the  pleuro-visceral  ganglia  of  the  two  sides  form  a  stout 
ganglionic  band  encircling  the  oesophagus  in  the  region  of 
the  cerebral  ganglia.  The  pallial  nerves  radiate  from  the 
lateral  portions  of  this  half-ring,  and  the  pair  of  visceral 
nerves  arise  from  the  ventral  portion.  The  visceral  cords 
pass  backwards  on  either  side  of  the  vena  cava,  and,  after 
giving  off  the  branchial  nerves,  are  prolonged  posteriorly  as 
far  as  the  post-anal  papilla,  behind  which  Mr.  Kerr  has 
recognised  an  apparent  anastomosis.  Mr.  Kerr  adds  that 
in  this  case  "  the  homologue  of  the  pleuro-visceral  cord  of 
Chiton  is  not  merely  the  posterior  sub-cesophageal  nerve- 
mass,  but  rather  the  two  lateral  portions  of  this,  together 
with  the  post-branchial  prolongations  which  run  on  either 
side  of  the  vena  cava.  The  mesial  part  of  the  posterior 
sub-cesophageal  nerve-mass  would  therefore  be  a  secondary 
fusion  between  the  nerve-masses  of  the  two  opposite 
sides." 

In  his  suggested  homology  of  this  possible  post-anal 
{i.e.,  supra- rectal)  commissure  of  the  visceral  nerves  in 
Nautilus  with  the  supra-rectal  "  commissure "  of  Chiton, 
Mr.  Kerr  has  undoubtedly  failed  to  appreciate  the  true 
nature  of  the  posterior  sub-cesophageal  loop  of  Nautilus,  as 
well  as  the  relation  of  the  visceral  nerves  to  the  pleuro- 
visceral  cords  of  Chiton.  The  explanation  of  the  Cephalo- 
pod  nervous  system  is  most  readily  found  by  comparing  it 
with  that  of  Dentalium,  whose  organisation  in  many  respects 
supplies  connecting  links  between  that  of  the  Cephalopoda 
and  that  of  the  primitive  prae-torsional  Gastropod  or 
primitive  Pelecypod.        In  Dentalium  (22,  p.  401)  we  find 


THE  MORPHOLOGY  OF  THE  MOLLUSC  A.  53 

a  pair  of  post-anal  prolongations  of  the  visceral  nerves 
precisely  resembling  those  described  by  Kerr  in  Nautilus ; 
yet  in  Dentalium,  owing  to  the  smaller  degree  of  concen- 
tration or  cephalisation  which  has  taken  place  in  the 
nervous  system,  it  is  easy  to  see  that  the  typical  sub-intes- 
tinal visceral  commissure  exists  as  in  Gastropods  and 
Pelecypods.  The  posterior  sub-cesophageal  nerve-mass 
of  Cephalopods  has  clearly  been  produced,  not,  as  Mr. 
Kerr  suggests,  by  a  secondary  fusion  of  the  pleuro- visceral 
nerve-masses  of  the  two  opposite  sides,  but  by  a  simple 
shortening  of  the  visceral  loop  as  it  occurs  in  Dentalium. 
This  would  bring  the  visceral  ganglia  into  continuity 
with  the  pleural  ganglia  and  with  one  another, — a  process 
of  condensation  with  which  we  are  already  familiar  in  the 
Tenioglossa  and  the  Euthyneura  among  Gastropoda. 

It  may  here  be  mentioned  that  Willey's  simultaneous 
account  (26)  of  the  visceral  nerves  of  Nautilus,  while  con- 
firming Mr.  Kerr's  observations  as  to  the  existence  of  post- 
anal prolongations  of  a  pair  of  visceral  nerves,  differs  from 
his  statement  as  to  their  origin.  Willey  states  that  the 
nerves  supplying  the  post-anal  papilla  arise  independently 
from  the  sub-cesophageal  visceral  loop,  although  at  their 
origin  they  are  adjacent  to  the  branchial  nerves  and  for  a 
large  part  of  their  course  are  actually  contiguous  with  them. 
The  significance  of  this  separation  is  not  remarked  upon  by 
Willey  ;  but  if  the  separation  really  exists  it  is  certainly  a 
difficulty  in  the  way  of  his  contention  that  the  post- 
anal papilla  represents  an  approximated  posterior  pair  of 
branchial  sense-organs,  since  the  anterior  osphradium  and 
both  gill-plumes  are  all  innervated  from  the  outer  visceral 
nerve. 

Etithyneurism. — Since  the  publication  of  Spengel's  paper 
on  the  olfactory  organ  and  nervous  system  of  Mollusca,  a 
division  of  the  Gastropoda  into  two  groups,  the  Strep- 
toneura  and  the  Euthyneura,  has  been  generally  adopted. 
This  classification  has  been  accepted,  moreover,  not  merely 
as  an  expression  of  the  anatomical  facts  concerning  the 
condition  of  the  visceral  loop  in  the  two  groups,  but  as  a 
classification  of  phylogenetic  significance.      It  is  to  be  in- 


54  SCIENCE  PROGRESS. 

ferred  that  the  two  groups  have  been  independently  derived 
from  a  common  type  of  archi-Gastropod,  possessing  an  un- 
twisted visceral  loop — the  Prosobranchs  (Streptoneura)  by 
the  twisting  of  the  loop,  the  Opisthobranchs  and  Pulmonates 
(Euthyneura)  by  the  mere  shortening  and  concentration  of 
the  untwisted  loop.  This  view  derives  support  from  the 
fact  that  the  persistent  ctenidium  retains  its  primitive  posi- 
tion on  the  right  side  of  the  body  in  Opisthobranchs,  while 
in  Prosobranchs  it  shows  a  marked  displacement  and  lies 
on  the  left  side.  Bouvier's  observations  on  Actceon 
( =  Tornatella),  however,  have  completely  altered  the  posi- 
tion of  affairs.  Actceon  is  a  very  primitive  Opisthobranch, 
as  may  be  inferred  from  the  high  development  of  its  shell, 
the  persistence  of  its  operculum,  and  the  absence  of  pleuro- 
podial  fins.  Bouvier  tell  us  (4)  that  Actcson  resembles  the 
Prosobranchs,  not  only  in  these  points,  but  also  in  possess- 
ing a  distinct  twist  of  the  visceral  loop  (streptoneurism, 
chiastoneurie).  The  ctenidium  is  innervated  from  a  supra- 
intestinal  ganglion,  which  lies  on  the  left  side  of  the  body. 
We  are  accordingly  led  to  the  conclusion  that  the 
euthyneurous  condition  of  Opisthobranchs  and  Pulmonates 
has  not  been  directly  inherited  from  the  orthoneurous 
ancestors  of  the  Gastropoda,  but  has  been  derived  from  a 
previously  streptoneurous  condition.  In  other  words  the 
Opisthobranchs  and  Pulmonates  have  descended  from 
Prosobranch  ancestors,  and  the  right-sided  position  of  the 
gill-plume  in  Opisthobranchs  is  not  primitive,  but  the  result 
of  a  secondary  process  of  detorsion. 

Orthoneuroidism. — Without  going  further  into  the 
matter  it  may  also  here  be  mentioned  that  the  supra-in- 
testinal commissure  has  been  recently  discovered  in  various 
species  of  Nerita,  Neritina,  and  Navicella  by  Boutan  (2), 
Bouvier  (3^),  and  Haller  (11) — a  discovery  which  de- 
stroys the  last  refuge  of  orthoneurism  in  Prosobranchiate 
Gastropods.  Streptoneurism  may  now  be  affirmed  of  all 
Prosobranchiate  Gastropods. 

Origin  of  the  Moliuscan  nervous  system. — The  attempts 
of  previous  writers  to  explain  the  relations  of  the  nervous 
system   of   Mollusca   have   been    based   almost   exclusively 


THE  MORPHOLOGY  OF  THE  MOLLUSC  A.  55 

upon  comparisons  with  the  fully  constituted  nervous 
systems  of  such  types  as  the  Turbellaria  and  Annelida. 
With  Thiele's  theory  of  the  Turbellarian  ancestry  of  the 
Mollusca  I  have  already  dealt,  and  I  do  not  propose  to 
deal  with  the  Annelidan  hypothesis,  since  this  theory  can- 
not provide  any  satisfactory  explanation  of  the  high  develop- 
ment of  the  pleuro-visceral  nervous  system  of  the  Mollusca. 
Those  authors  who,  like  Thiele  and  Pelseneer,  homologise 
both  the  pleural  and  pedal  centres  of  the  Mollusca  with  the 
ventral  cords  of  Annelids,  base  their  view  upon  the  sup- 
posed origin  of  the  pleural  centres  from  the  pedal  cords. 
This  derivation  I  have  already  shown  in  this  article  to  be 
completely  erroneous.  Pelseneer's  theory  of  the  origin  of 
the  Mollusca  from  Polychsete  ancestors  (18a),  and  all 
theories  which  seek  the  origin  of  the  Mollusca  in  the 
specialised  representatives  of  any  of  the  vermiform  groups, 
may  at  once  in  my  opinion  be  dismissed  from  considera- 
tion. 

Apart  from  matters  of  minor  importance  it  will,  I  think, 
be  conceded  that  the  following  cardinal  points  in  regard 
to  the  morphology  of  the  Molluscan  nervous  system  have 
been  established  by  the  facts  and  arguments  which  have 
been  presented  in  this  article  : — 

(1)  That  the  pleural  ganglia  have  not  been  derived  by 

segregation  from  the  ventral  or  pedal  cords. 

(2)  That  the  pleural,   visceral,   and  abdominal  ganglia 

of  Gastropoda  form  a  group  of  dorsal  nerve- 
centres — the  two  former  owing  to  their  dif- 
ferentiation in  the  immediate  neighbourhood  of 
the  velum,  and  the  latter  owing  to  its  differentia- 
tion from  the  mid-dorsal  wall  of  the  body  (floor 
of  mantle-cavity). 

(3)  That   the  dorso-lateral  nerve-ring  of  Amphineura 

is  primitive  and  is  represented  in  other  groups 
of  Mollusca  by  both  the  pallial  and  visceral 
nerve  loops,  or  their  derivatives. 

(4)  That  the  sub-intestinal  position  of  the  visceral  loop 

in  all  groups  except  the  Amphineura  is  a 
secondary  one,  which  has  been  rendered  possible 


56  SCIENCE  PROGRESS. 

only  by  the  decentralisation  of  the  primitive 
pleuro-visceral  nervous  system,  and  its  separa- 
tion into  special  ganglia  and  nerves,  the  latter 
being  formed  ontogenetically  as  fibrous  out- 
growths from  the  ganglionic  centres. 
Venturing  now,  in  conclusion,  upon  more  speculative 
ground,  I  believe  that  the  embryonic  relations,  to  which  I 
have  drawn  attention,  between  the  pleural  and  visceral 
ganglia  and  the  ciliated  band  are  of  phylogenetic  importance. 
It  has  long  puzzled  me  that  the  larval  forms (trochospheres)  of 
two  groups  so  closely  allied  as  the  Annelida  and  Mollusca, 
while  presenting  a  close  similarity  in  general  structure, 
should  differ  so  remarkably  in  regard  to  their  nervous 
system.  The  Annelid  trochosphere  has  a  nerve-ring 
beneath  its  ciliated  band,  while  the  Molluscan  trocho- 
sphere has  none.  In  this  respect  the  Molluscan  trocho- 
sphere appears  to  be  less  primitive  than  that  of  the 
Annelida.  The  explanation  of  this  now  appears  to  me  to 
be  as  follows.  In  the  evolution  of  the  Annelida  the  proto- 
troch  and  nerve-ring  remained  for  a  long  time  unmodified, 
and  did  not  share  in  the  elongation  of  the  postero-ventral 
region  of  the  body  which  gave  rise  to  the  trunk  of  the 
Annelid.  This  would  explain  the  absence  of  the  dorsal 
nerve-ring  in  the  adult  Annelid,  provided  that  the  nerve- 
ring,  together  with  the  prototroch,  came  to  have  merely  a 
larval  significance, — as  actually  happens  in  the  ontogeny  of 
Annelids  to-day.  On  the  other  hand,  in  the  evolution  of 
the  Mollusca  from  the  same  simple  type  of  ancestor,  the 
whole  body  must  have  shared  in  the  elongation — the  proto- 
troch and  nerve-ring  as  well  as  the  more  ventrally  placed 
parts  of  the  body.  This  elongated  nerve-ring  I  identify 
with  the  pleuro-visceral  ring  of  Amphineura,  although  the 
phyletic  connection  between  the  nerve-ring  and  the  ciliated 
band  is  inferred  from  the  development  of  certain  Gastro- 
pods rather  than  from  the  Amphineura  themselves.  As  a 
larval  adaptation  for  conveniences  of  natation  I  imagine 
that  a  separation  became  gradually  effected  in  embryonic 
life  between  the  ciliated  ring  and  the  nerve-ring,  the  former 
becoming  restricted  to  the  anterior  end  of  the  larval  body, 


THE  MORPHOLOGY  OF  THE  MOLLUSC  A.  57 

while  the  latter  became  more  and  more  extended  pari  passu 
with  the  elongation  of  the  trunk.  Such  a  separation  is  to 
some  extent  paralleled  in  the  development  of  Holothurians 
from  the  Auricularia  larva,  as  described  by  Semon.  On 
this  theory  alone  can  I  explain  to  myself  the  absence  of  the 
ancestral  nerve-ring  in  the  trochospheres  of  Mollusca,  and 
I  find  some  support  for  this  view  in  the  ontogeny  of  Nemer- 
tines.  The  lateral  nerve-cords  in  this  group  have  the  same 
relation  to  the  gut  and  brain  as  have  the  pleuro-visceral 
cords  of  Chiton,  since  they  form  a  dorso-lateral  ring,  the 
posterior  commissural  portion  passing  above  the  rectum. 
In  Nemertines  there  can  be  very  little  doubt  that  this 
nerve-ring  has  been  derived  phyletically  by  the  elonga- 
tion of  a  nerve-ring  which  underlay  the  ciliated  band  of  a 
more  or  less  Pzlidzum-like  ancestor,  as  it  underlies  the 
ciliated  band  of  the  Pi/idzum-laxva.,  although  this  phyletic 
origin  is  disguised  by  the  profound  metamorphosis  which 
breaks  the  continuity  of  the  ontogenetic  record  in  Nemer- 
tines. On  this  theory  of  course  the  lateral  cords  of  Nemertines 
do  not  correspond  to  the  ventral  cords  of  Annelids.  The 
latter  are  represented  by  the  general  ventral  plexus  of 
Nemertines  and  by  the  pedal  plexus  or  cords  of  Mollusca. 
These  ventral  nervous  systems  appear  to  bear  relations  to 
the  dorso-lateral  ring-nerve  similar  to  those  of  the  subum- 
brellar  plexus  of  Medusae  to  the  circumferential  nerve-ring. 
It  will  be  recognised  from  these  remarks  that  the 
conclusions  to  which  I  have  arrived  present  distinct  points 
of  agreement  with  those  of  Balfour  (1,  p.  37&)  and  Sedg- 
wick (21)  on  the  same  subject,  although  attained  throughout 
by  an  independent  series  of  inductions.  With  both  these 
writers  I  agree  in  tracing  back  the  Molluscan  nervous 
system  to  a  primitively  annular  type,  such  as  might  be 
expected  to  exist  in  a  Ccelenterate  ancestor.  Balfour 
derives  the  whole  Molluscan  nervous  system  from  a 
peripheral  nerve-ring  which  followed  the  course  of  a  hypo- 
thetical ciliated  ring:  ;  Sedgwick  derives  it  from  a  broad 
plexus  surrounding  an  elongated  blastopore,  such  as  occurs 
in  existing  Actinians.  Sedgwick's  theory  was  practically 
an  alternative  to  Balfour's,  but  I   find  myself  able  to  give  a 


5»  SCIENCE  PROGRESS. 

partial  acceptance  to  both  these  views.  For  the  nervous 
system  of  Mollusca  appears  to  me  to  consist  of  two  parts,  a 
circumferential  ring  and  a  peri-blastoporal  plexus.  The 
circumferential  ring,  which  was  primitively  associated  with 
a  ciliated  ring,  is  represented  by  the  pleuro-visceral  nervous 
system,  which  I  have  shown  to  possess  significant  relations 
with  the  velum  or  prototroch  of  the  larva  ;  and  the  peri- 
blastoporal  plexus  seems  to  me  to  be  recognisable  in  the 
pedal  nervous  system,  which  in  primitive  Molluscs  has  a 
very  diffuse  plexus-like  arrangement,  and  in  Amphineura, 
at  any  rate,  reveals  its  peri-blastoporal  character  in  the 
cerebro-pedal  connectives  in  front  and  its  connectives  with 
the  supra-rectal  abdominal  ganglion  behind. 

BIBLIOGRAPHY. 

(i)   Balfour,  F.  M.     Comparative  Embryology,  ii.,  1885. 

(2)  BOUTAN.     Arch.  Zool.  Exp.  (3),  i.,  pp.  221-265,  1893. 

(3)  Bouvier.     Systeme  Nerveux  des  Prosobranches.     Ann.  Sci. 

Nat.  (7),  iii.,  1887. 
{id)  Bouvier.     Comptes  Rendus,  cxiv.,  p.  1281,  1892. 

(4)  BOUVIER.      Comptes  Rendus,  cxvi.,  pp.  68-70. 

(5)  Duvernoy.     Mem.  sur  le  systeme  nerveux  des  Mollusques 

Acephales.     Mem.  Acad.  Sci.  Paris,  xxiv. 

(6)  ERLANGER,  R.  von.     Zur  Entwicklung  der  Paludina  vivipara, 

I.  u.  II.  Theil.     MorpJi.  Jahrbuch,  xvii.,  1891. 

(7)  ERLANGER,    R.  VON.     Zur   Entwicklung   von    Bithynia    ten- 

taculata.     Mitth.  Zool.  Stat.  Neapel.  x.,  1892. 

(8)  HALLER,   BELA.     Die  Organisation  der  Chitonen  der  Adria. 

Arb.  Zool.  Inst.  Wien,  1882-3. 

(9)  HALLER,    BeLA.       Untersuchungen    Liber    marine     Rhipido- 

glossen,  I.     Morph.Jahrb.,  ix.,  1884. 

(10)  Haller,  Bela.    Die  Morphologie  der  Prosobranchier.   Morph. 

Jahrb.,  xiv.,  1888. 

(11)  HALLER,  BELA.     Studien    liber    Docoglosse  u.  Rhipidoglosse 

Prosobranchier,  4I-0,  1894. 

(12)  HUXLEY  and  PELSENEER.      Report  on  Spirula.     "Challenger" 

Reports,  Zool,  part  lxxxiii.,  Appendix,  1895. 

(13)  KERR,  J.  G.     On  some    Points   in    the  Anatomy  of  Nautilus 

pompilius.     Proc.  Zool.  Soc,  part  iii.,  1895. 

(14)  Korschelt     u.     Heider.       Lehrbuch     der     Entwicklungs 

geschichte,  iii.,   1893. 


THE  MORPHOLOGY  OF  THE  MOLLUSC  A.  59 

(15)  KOWALEVSKY,  A.     Embryogenie  du  Chiton  polii.     Ann.  Mus. 

Hist.  Nat.  Marseille.,  Zool.,  i.,  1883. 

(16)  LANG,  ARNOLD.     Lehrbuch  der  Vergl.  Anat,  3  heft. 

(17)  Lankester,     E.      Ray.       Mollusca.      Encycl.    Brit.,    ninth 

edition. 

(18)  PELSENEER.       Contribution    a    l'etude    des    Lamellibranches. 

Arch,  de  Biol.,  xi.,  p.  166,  pi.  vi.,  fig.  3,  1891. 
(i8#)   PELSENEER.     Classification  Generale  des  Mollusques.     Bull. 
Sci.  France  et  Belg.,  xxiv.,  p.  346,  1892. 

(19)  PELSENEER.     Introduction  a  l'etude  des  Mollusques.  Bruxelles, 

1894. 

(20)  PLATE.     Bemerk.    lib.    d.    Phylogenie   u.   d.     Entstehung    d. 

Asymmetrie  d.  Mollusken.     Spengel's  Zool.  Jahrbiicher,  Abth. 
f.  Anat.  u.  Ont.,  ix.,  i.,  p.  169,  1895. 

(21)  Sedgwick,  Adam.     On  the  Origin  of  Metameric  Segmenta- 

tion.    Quart.  Jour.  Micr.  Sci.,  xxiv.,  1884. 

(22)  SlMROTH.      Bronn's  Klassen  u.  Ordnungen   des   Thier-Reichs . 

Mollusca.  I.  Amphineura  u.  Scaphopoda,   1892-94. 

(23)  Thiele,    J.       Ueber  Sinnesorgane   der   Seitenlinie  und    das 

Nervensystem  von  Mollusken.    Zeit.f.   IViss.  Zool,  xlix.,  pp. 
385-432,  1890. 

(24)  Thiele,  J.    Die  Stammesverwandschaft  der  Mollusken.    Jena 

Zeit.,  xxv.,  p.  480,  1 89 1. 

(25)  Thiele,  J.     Beitrage  zur  Kenntniss  der   Mollusken.    Zeit.  J. 

Wiss.  Zool,  liii.,  p.  578,  1892. 

(26)  WlLLEY,  A.     Natural  Science,  vi.,  p.  412,  1895. 

Walter  Garstang. 


THE    RESERVE    MATERIALS    OF    PLANTS. 

( Concluded. ) 

THE  position  of  the  glucosides  in  vegetable  metabolism 
has  been  for  a  long  time  a  subject  of  considerable 
controversy,  which  has,  however,  been  most  largely  con- 
cerned with  tannin.  The  details  of  its  formation,  its  locali- 
sation and  its  fate  have  been  discussed  at  great  length,  but 
the  discussion  has  been  largely  conducted  on  the  lines  of 
hypothesis  and  analogy  rather  than  experiment.  The  con- 
clusions reached  by  such  a  method  of  treatment  have  some- 
what hastily  been  applied  to  all  glucosides,  as  if  tannin  were 
eminently  the  typical  one.  There  are  now  reasons  for 
thinking  that  so  far  from  this  being  the  case  it  is  especially 
exceptional. 

The  number  of  oflucosides  known  has  increased  con- 
siderably  in  recent  years  as  our  investigations  into  plant 
metabolism  have  been  pursued,  and  increasing  knowledge 
of  them  forces  the  conviction  more  and  more  upon  us  that 
they  take  a  more  or  less  active  share  in  the  nutritive  pro- 
cesses, possibly  direct,  but  more  probably  through  certain 
of  the  products  to  which  they  give  rise  on  decomposition. 
They  are  not  so  markedly  reserve  stores  for  seeds  as  are 
many  of  the  bodies  we  have  already  discussed,  though  many 
seeds,  and  notably  many  of  those  of  plants  of  the  Rosaceae 
and  Cruciferse  and  orders  allied  to  these,  contain  them  in 
quantity  together  with  other  reserves.  They  occur,  how- 
ever, in  other  parts  of  the  plant,  not  quite  as  circulating 
reserves,  but  rather  as  transitory  stores  for  more  localised 
growth  and  nourishment.  The  old  advocates  of  their 
nutritive  functions  rested  their  case  largely  on  the  presence 
of  sugar  in  the  glucoside  molecule,  and  held  that  this  is  the 
body  which  is  available  for  the  constructive  processes  of  the 
organism.  There  are,  however,  reasons  for  holding  that 
this  view  is  too  limited  a  one.  and  that  some  of  the  other 
products  of  their  decomposition  may  be  as  valuable  as  the 
sugar,  if  not  of  even  greater  importance. 


THE  RESERVE  MATERIALS  OF  PLANTS.  61 

The  glucosides  that  have  attracted  most  attention  during 
recent  years  are  those  which  occur  in  the  plants  belonging  to 
the  families  already  mentioned,  the  Rosacese,  the  Cruciferae, 
and  other  orders  which  show  affinities  with  these.  These 
plants  contain,  very  widely  distributed  through  their  tissues, 
amygdalin  and  sinigrine  or  myronate  of  potash  respectively. 
Of  these  the  former  is  perhaps  the  most  interesting,  as 
from  its  decomposition  by  enzyme  agency  there  is  produced 
hydrocyanic  acid,  which  has  always  been  regarded  as  most 
virulent  in  its  action  upon  all  living  things.  The  existence 
of  this  noxious  principle  in  the  plant  has  perhaps  been  partly 
the  cause  of  the  readiness  of  botanists  to  class  the  glucoside 
which  yields  it,  and  hence  the  whole  class  of  glucosides, 
among  the  products  of  excretion. 

The  localisation  of  the  amygdalin  is  calculated  to  throw  a 
good  deal  of  light  upon  the  question  of  its  probable  function 
and  fate.  For  many  years  attention  has  been  given  to  it, 
at  first,  owing  to  imperfect  methods  of  research,  without 
much  practical  result.  Improvement  in  technique  has, 
however,  yielded  very  valuable  results,  and  has  led  to 
conclusions  greatly  at  variance  with  those  held  thirty 
years  ago.  Thome  (60),  who  wrote  in  1865  upon  the 
nutritive  materials  contained  in  the  sweet  and  bitter  al- 
monds respectively,  said  that  amygdalin  occurs  in  the 
parenchyma  of  the  cotyledons  of  both  varieties,  and  that 
its  corresponding  enzyme,  emulsin,  is  only  present  in  the 
bitter  almond,  being  localised  in  the  weak  fibrovascular 
bundles  that  are  in  the  cotyledons.  This  statement  has 
been  shown  to  be  the  exact  converse  of  the  truth.  Portes 
(61),  who  worked  twelve  years  later,  showed  that  the  gluco- 
side and  the  enzyme  occupy  different  parts  of  the  seed,  the 
former  being  distributed  in  the  cotyledonary  parenchyma, 
while  the  latter  is  to  be  found  in  the  axis  of  the  embryo. 
Pfeffer  (62),  in  his  Pflanzenphysiologie,  suggests  that  this 
localisation  is  not  accurate,  and  that  the  two  bodies  probably 
occupy  the  same  cells,  the  only  degree  of  separation  being 
that  the  ferment  is  in  the  protoplasm  and  the  glucoside  dis- 
solved in  the  cell-sap.  In  1887  Johansen  (63)  by  chemical 
methods  succeeded  in  ascertaining  the  distribution  of  the 


62  SCIENCE  PROGRESS. 

two  bodies  in  the  seeds.  He  found  the  emulsin  to  be  pre- 
sent in  both  varieties  of  the  almond,  and  to  be  chiefly 
localised  in  the  fibrovascular  bundles.  He  further  ascer- 
tained that  the  glucoside,  amygdalin,  is  only  present  in  the 
cotyledonary  parenchyma  of  the  bitter  one.  The  absence 
of  the  glucoside  from  the  seed  of  the  sweet  almond  points, 
of  course,  to  the  conclusion  that  even  if  it  be  a  nutritive 
body  it  is  not  one  of  very  great  prominence  in  the  nutrition 
of  the  embryo  on  germination. 

Guignard  has  published  within  the  past  few  years  a 
series  of  researches  which  deal  primarily  with  the  localisa- 
tion of  the  enzymes  which  decompose  the  glucosides,  but 
which  incidentally  throw  a  certain  light  upon  the  occurrence 
and  meaning  of  the  latter.  In  his  first  papers  (64)  he  treats 
of  the  amygdalin  which  is  found  in  the  almond  and  in  the 
cherry  laurel,  in  the  latter  of  which  it  is  found  to  have  a 
fairly  copious  distribution.  He  confirms  Johansen  as  to  its 
position  in  the  seed  of  the  almond,  and  still  more  closely 
localises  the  enzyme.  In  the  laurel  (Prunus  lauro-cerasus) 
the  parenchyma  of  the  leaves  as  well  as  of  the  axis  appears 
to  contain  it  in  solution  in  the  cell-sap.  The  occurrence  of 
the  emulsin  is  confined  to  the  neighbourhood  of  the  con- 
ducting- tissues,  it  being  chiefly  found  in  the  endodermis 
round  the  fibrovascular  bundles.  In  the  bundles  of  the  axis 
of  the  embryo  in  the  almond  the  ferment  occurs  in  the  many 
layered  pericycle,  chiefly  outside  the  bast.  The  distribution 
of  the  amygdalin  is  not  definitely  known.  It  may  happen 
that  the  fluid  sap  containing  it  may  travel  along  the  cellular 
tissue,  and  the  occurrence  of  the  ferment  which  decomposes 
it,  in  the  immediate  neighbourhood  of  the  conducting  tissues, 
suggests  that  it  is  charged  with  the  duty  of  preparing  from 
the  glucoside  certain  nutritive  products  that  may  easily  make 
their  way  to  the  conducting  tissues,  and  so  travel  to  the 
actual  seats  of  constructive  metabolism.  That  sugar  so 
travels  is  of  course  a  matter  of  every-day  experience,  but 
whether  or  no  the  remaining  products  are  made  use  of  in  a 
similar  way  is  open  to  discussion.  On  the  other  hand  it 
may  be  that  the  amygdalin  descends  by  the  conducting 
tissue  of  the  bast  and  undergoes  decomposition  as  it  passes 
downwards,  yielding  simpler  products  to  the  young  cortex. 


THE  RESERVE  MATERIALS  OF  PLANTS.  63 

In  the  face  of  the  problem  of  the  utilisation  of  the  bodies 
resulting  from  the  action  of  emulsin  upon  amygdalin  great 
importance  must  be  ascribed  to  the  recent  work  published 
by  Treub  on  the  occurrence  and  meaning  of  hydrocyanic 
acid  in  the  tissues  of  Pangium  edule  (65),  one  of  the 
Bixacese.  This  compound,  according  to  the  author,  does 
not  occur  as  a  glucoside,  but  in  the  free  condition,  and  is 
present  in  relatively  large  amount.  Greshoff  found  more 
than  1  per  cent,  to  be  hydrocyanic  acid  of  the  dry  weight 
of  the  plant  in  one  sample  among  many  others  analysed. 
A  brief  resumi,  of  the  author's  conclusions  seems  not  to  be 
out  of  place  here,  as  throwing  light  upon  the  question  of 
the  nutritive  value  of  the  glucoside  of  the  laurel.  Indeed 
it  seems  not  improbable  that  the  hydrocyanic  acid  itself  may 
be  regarded  as,  in  some  cases  at  least,  a  reserve  material. 

Treub  has  made  a  careful  investigation  into  the 
localisation  of  this  principle  in  the  plant,  using  as  his 
method  the  reaction  given  in  the  formation  of  Prussian 
blue  when  hydrocyanic  acid  comes  in  contact  with  a  ferric 
salt  in  the  presence  of  hydrochloric  acid.  The  reaction  is 
very  distinct  and  takes  place  well  in  the  interior  of  the 
cells,  causing  those  which  contain  the  hydrocyanic  acid 
to  stand  out  with  great  distinctness. 

In  the  whole  of  the  adult  axis,  both  stem,  root  and 
peduncles,  he  finds  it  to  exist  in  quantity  in  the  conducting 
tissue  of  the  bast  and  pericycle.  In  the  leaves  it  is  still  in  the 
same  regions,  but  is  more  widely  spread,  nearly  all  the 
parenchymatous  tissue  of  the  blade  containing  more  or  less 
of  it.  The  epidermis  especially  is  noteworthy,  showing  it 
present  in  the  basal  cells  of  the  hairs  which  the  leaves  bear, 
and  in  certain  idioblasts  which  contain  also  crystals  of 
oxalate  of  lime.  In  the  young  fruits  and  those  which  are 
growing  a  considerable  quantity  is  present,  partly  in  the 
bast  and  partly  in  parenchyma  outside  the  conducting  tissue. 
In  the  seeds  there  is  an  accumulation  in  the  peripheral 
layers  of  the  endosperm  and  in  other  cells  of  the  same 
tissue  abutting  on  the  embryo. 

In  these  regions,  and  in  the  cortex,  and  sometimes  the 
pith  of  the  axis,   Treub  describes  the  hydrocyanic  acid  as 


64  SCIENCE  PROGRESS. 

existing  in  special  cells  which  are  sharply  marked  off  from 
the  others  round  them  when  stained  as  above  described. 
These  special  cells  vary  a  good  deal  in  number,  apparently 
according  to  the  amount  of  the  acid  present  in  the  plant, 
and  have  no  very  specially  regular  distribution.  Indeed  it 
seems  probable  that  any  cell  of  the  tissue  may  become  a 
centre  of  deposition  of  the  acid.  Generally,  if  not  quite 
isolated,  they  only  occur  two  or  three  together.  Certain  of 
the  fibres  of  the  pericycle  may  be  observed  almost  similarly 
isolated. 

Treub  further  says  that  these  special  cells  of  the  cortex 
or  of  the  pith  derive  their  supply  of  hydrocyanic  acid  from  the 
conducting  tissue  of  the  bast  and  that  the  amount  of  them 
and  consequently  of  the  acid  varies  with  the  condition  of 
the  stem. 

Tracing  the  hydrocyanic  acid  upwards  through  the  axis 
by  means  of  longitudinal  sections  it  can  be  found  to  extend 
throughout  its  whole  length,  but  to  disappear  at  a  little  dis- 
tance from  the  growing  point,  the  apical  meristem  of  which 
contains  none. 

It  is  impossible  to  avoid  being  struck  with  the  similarity 
here  exhibited  to  the  fate  of  sugar,  amides,  etc.,  which  as 
we  have  seen  can  be  traced  up  to  the  seats  of  constructive 
metabolism  and  there  cease,  apparently  giving  rise  to 
protoplasm.  If  this  be  so,  the  hydrocyanic  acid  must  be 
regarded  as  a  plastic  material,  unsuitable  as  at  first  sight  it 
would  appear  for  that  purpose. 

This  view  is  supported  by  several  observations  which 
the  author  details  at  some  length.  He  finds  that  in  the 
apices  of  young  shoots  which  have  suffered  an  arrest  of 
growth,  there  are  more  of  the  special  cells  containing  the 
hydrocyanic  acid  than  there  are  in  similar  ones  which  are 
undergoing  rapid  elongation.  That  is,  where  there  is  active 
consumption  of  plastic  material  there  is  no  accumulation  of 
the  acid,  but  where  plastic  substances  are  compelled  to  remain 
unused,  hydrocyanic  acid  is  one  of  such  stored  bodies. 

Another  series  of  observations  considerably  strengthens 
this  view,  while  it  points  more  definitely  to  the  ultimate 
purpose  of  the  acid.      In  many  of  the  special  cells  the  latter 


THE  RESERVE  MATERIALS  OF  PLANTS.  65 

may  be  seen  to  be  accompanied  by  quantities  of  proteid 
substance.  Taking  young  cells  near  the  apex  of  the  shoot 
the  special  cells  contain  the  hydrocyanic  acid  alone,  showing 
that  it  precedes  proteid  in  the  time  of  its  occurrence.  A 
little  farther  back  the  proteid  can  be  detected,  and  gradually 
as  sections  are  taken  at  increasing  distances  from  the  apex 
it  increases  in  amount  while  the  acid  diminishes.  As  the 
active  life  of  the  cells  becomes  less  and  less  vigorous,  the 
proteid  becomes  more  and  more  preponderating  in  the  cell 
contents,  and  ultimately  cells  are  found  which  contain 
proteid  only,  the  hydrocyanic  acid  having  all  disappeared. 
The  same  succession  of  events  can  be  seen  if  the  develop- 
ment of  the  pericyclic  fibres  be  traced  towards  the  apex  of 
the  stem. 

There  seems  from  these  observations  to  be  very  strong 
reasons  for  supposing  that  hydrocyanic  acid  is  a  nutritive 
substance  and  leads  at  any  rate  in  these  plants  to  the 
formation  of  proteid. 

Treub  holds  that  this  is  its  immediate  function  ;  he 
believes  it  to  be  primarily  formed  in  the  leaves,  principally 
in  the  basal  cells  of  the  hairs  and  the  idioblasts  with  calcic 
oxalate  in  the  epidermis  of  the  leaves.  Thence  it  makes 
its  way  to  the  conducting  tissues  of  the  bast  and  pericycle 
and  travels  to  the  apical  meristems.  It  is  thus  primarily  a 
body  originating  only  in  the  constructive  processes,  and  not, 
as  in  the  cases  of  the  almond  and  cherry  laurel,  the  product 
of  a  decomposition  of  a  glucoside.  Indeed  Treub  says  very 
emphatically  :  "  L'acide  cyanhydrique  du  Pangium  edule 
n'est  pas  un  produit  de  decomposition  ou  de  desassimila- 
tion,"  basing  the  statement  on  both  indirect  and  direct 
arguments.  The  former  are  founded  on  the  localisation  of 
the  product  in  the  bast  and  pericycle  and  its  evident  trans- 
portation by  the  bast  tissue.  The  latter  involve  the 
consideration  of  its  localisation  with  a  material  which 
serves  as  a  temporary  proteid  reserve  in  the  same  elements 
of  the  tissues,  and  the  order  of  appearance  and  disappear- 
ance of  the  two  substances  in  such  special  cells. 

That  hydrocyanic  acid   can  subserve  not  only  the  for- 
mation of  temporary  reserves  of  proteid  but   can  be  used, 

5 


66  SCIENCE  PROGRESS. 

immediately  after  its  first  formation,  by  the  leaves  in  which 
it  is  formed  also  appears  certain.  When  plants  whose 
leaves  contain  it  are  put  for  some  days  in  the  dark  the  acid 
gradually  disappears,  and  as  usual  in  such  cases  their  whole 
metabolism  suffers.  On  being  again  illuminated  the  vital 
processes  gradually  resume  their  activity.  If  a  plant  be 
put  in  the  dark  till  nearly  all  the  acid  has  gone  from 
the  leaves  and  then  it  be  brought  into  the  light,  the  little 
that  remains  is  soon  removed  by  the  returning  activity  of 
the  metabolism. 

That  the  acid  is  used,  and  not  simply  transported  from 
the  leaves,  can  be  shown  in  another  way,  by  cutting  a 
circular  section  through  the  conducting  tissue  of  the  petioles, 
when  removal  by  transport  becomes  impossible.  Yet  the 
hydrocyanic  acid  disappears  gradually. 

It  was  said  above  that  in  some  cases  the  hydrocyanic 
acid  itself  might  be  looked  upon  as  a  reserve  material. 
This  seems  to  be  the  case  in  the  special  cells  described  by 
Treub  in  the  cortex  of  plants  when  they  do  not  contain 
also  proteid.  In  such  cases  we  seem  to  have  temporary 
reservoirs  to  supply  local  and  transitory  needs  and  to 
supplement  the  current  passing  along  the  bast.  "  Dans 
les  endroits  non  on  pas  suffisamment  desservir  pour  le 
systeme  conducteur  liberien  ces  usines  locales  prennent 
naissance,  et  en  plus  grand  nombre,  a  mesure  que  la 
plante  a  on  aura  besoin  dans  ces  endroits  de  plus  de 
substances  plastiques."  Thus  in  the  older  part  of  the 
stem,  where  the  active  life  is  confined  almost  altogether 
to  the  cortex,  the  latter  contains  many  of  these  special  cells, 
while  they  are  absent  from  the  rest  of  the  fundamental 
tissue.  Where  they  are  present,  as  in  certain  portions  of 
the  petioles,  active  life  continues,  although  it  may  be  de- 
cadent in  other  parts. 

This  temporary  storage  comes  out  very  prominently  in 
the  cases  of  the  developing  fruit  and  seed.  At  the  base  of 
the  former,  just  above  its  point  of  junction  with  the  pedicel, 
there  is  a  very  marked  accumulation  of  the  hydrocyanic  acid, 
the  cells  staining  blue  under  the  treatment  described  being 
much   more   numerous  than   lower  down   the  stalk.       The 


THE  RESERVE  MATERIALS  OF  PLANTS.  67 

peripheral  layer  of  the  seed  in  its  young  condition  is 
also  supplied  very  fully  with  these  local  reservoirs.  We 
appear  to  have  here  a  deposit  laid  down  to  supplement  the 
regular  stream  which  is  passing  all  about  the  plant  by  means 
of  the  conducting  tissue  of  the  bast.  It  is  doubtless  derived 
from  the  circulating  supply,  for  if  the  latter  be  interrupted 
by  a  section  passing  across  the  stem  through  its  path,  the 
disappearance  of  the  acid  takes  place  from  the  bast  tissues 
below  the  wound  some  time  before  it  does  from  the  isolated 
special  cells  of  the  cortex. 

From  the  work  of  Treub  and  of  Guignard  then  it  seems 
increasingly  probable  that  the  glucosides  are  reserve 
materials,  and  not  simply  bye-products  or  products  of 
excretion.  Nor  is  it  apparently  only  the  sugar  in  them 
which  has  a  nutritive  value,  but  the  other  products  of  their 
decomposition  have  a  particular  part  to  play  in  the  meta- 
bolism. This  is  certainly  the  case  with  hydrocyanic  acid, 
and  no  doubt  further  investigation  will  show  that  it  is  the 
same  with  other  products  similarly  formed. 

Guignard  (66,  67)  has  made  similar  researches  to  those 
already  described  upon  the  plants  of  the  natural  orders 
Cruciferae,  Capparidaceae,  Tropceolacese,  Limnanthaceae, 
Resedaceae  and  Papayaceae  ;  which  all  contain  the  ferment 
myrosin,  a  body  capable  of  decomposing  more  than  one 
glucoside.  There  are  several  of  the  latter  compounds 
found  in  this  group  of  plants,  the  best  known  of  which  are 
sinio-rine,  ancj  sinalbine.  Siniorine  is  found  in  the  black 
mustard  (Brassica  nigra),  and  is  often  called  myronate  of 
potassium.  On  decomposition  it  yields  besides  sugar  a  vola- 
tile body,  sulphocyanate  of  Allyl,  and  potassic  hydrogen 
sulphate.  Sinalbine,  as  its  name  implies,  is  found  in  the 
white  mustard  (Sinapis  or  Brassica  alba).  When  decom- 
posed the  volatile  constituent  is  found  to  be  sulphocyanate 
of  orthoxybenzyl.  Others,  the  composition  of  which  is  not 
yet  fully  known,  are  those  of  the  watercress  {Nasturtium 
officinale)  which  yields  phenyl  propionic  nitrile,  the  common 
cress  {Lepidium  sativum)  affording  the  nitrile  of  alpha- 
toluic  or  phenylacetic  acid.  Though  the  fate  of  these 
complex   volatile  bodies  has    not    been  investigated,    it    is 


68  SCIENCE  PROGRESS. 

noteworthy  that  some  of  them  at  any  rate  contain  cyanogen 
compounds,  which  may  well  be  utilised  after  the  manner  of 
hydrocyanic  acid  itself  as  established  by  Treub. 

Their  distribution  in  the  plants  appears  to  follow  that  of 
the  amygdalin  in  the  Rosaceous  group,  but  very  little 
definitely  is  known  on  this  head.  The  enzyme  which  splits 
them  up  is  according  to  Guignard  always  found  in  special 
cells  which  do  not  contain  the  glucoside. 

Very  closely  allied  to  the  group  of  the  glucosides  is 
that  of  the  tannins,  about  the  importance  of  which  there 
has  been  a  good  deal  of  controversy.  Some  of  them  are 
no  doubt  glucosides,  yielding  among  their  products  of  de- 
composition gallic  acid  and  sugar.  Others  are  apparently 
not  so  associated  with  a  carbohydrate  group.  They  are 
very  widely  distributed,  and  often  occur  not  only  in  parts  of 
plants  which  are  devoted  to  storage  of  materials,  but  in  the 
tissues  where  active  metabolic  work  is  going  on.  The 
task  of  deciding  whether  or  no  they  serve  as  reserve 
materials  or  as  bye-products  is  consequently  not  easy. 

The    two    views    have   been    strenuously  supported  by 
different  writers.      Sachs,  while  working  on  the  germination 
of  the  Scarlet-runner  (68)  in  which  tannin  is  comparatively 
plentiful,    suggests    an    antithesis     between     carbohydrates 
and  proteids  on  the  one  hand,  and  the  tannins  and  colour- 
ing matters   on   the   other,    the   latter  being  in  his  opinion 
only  bye-products.      He  advances  in  support  of  his  view  the 
fact  that  they  appear  or  increase  with   renewed   growth  of 
the   embryo,    instead   of  diminishing    as   reserve   materials 
should  do.     Their  appearance  is  coincident  with  the  chemical 
changes    in    the    undoubted    reserves    which     lead     to   the 
utilisation   of  the   latter.      The  same   view  is   advanced  by 
Schell  (69),  who  suggests  that  in   some  cases,  however,   it 
may  be  a  nutritive  product.      In  the  germination  of  certain 
oily  seeds,  chiefly  of  plants  belonging  to  the  Boroginaceae, 
tannin,  which  is  present   in  addition   to   the  oil,  diminishes 
in   quantity  during  the  germination.      In   the   stem  of  the 
mature   plant    there    is    during    the    winter   a  considerable 
quantity    of  tannin    which   almost   vanishes    as  spring   ad- 
vances.   On  the  other  hand  he  finds  in  certain  almost  parallel 
cases  that  the  tannin  accumulates  instead  of  diminishing. 


THE  RESERVE  MATERIALS  OF  PLANTS.  69 

The  view  that  these  bodies  have  a  nutritive  value  has 
been  supported  with  some  emphasis  by  other  writers. 
Wigand  associated  it  very  closely  with  the  carbohydrates, 
and  thought  it  was  an  essential  factor  in  vegetable  meta- 
bolism. Wiesner  also  supported  the  view  of  its  carbohy- 
drate relationships,  and  indicated  a  probability  that  it  stands 
between  the  starch  and  cellulose  groups  and  the  great  class 
of  resins,  etc.  The  latter  relationship  has  been  again 
brought  forward  by  Hillhouse  (70),  who  found  in  Pinus 
sylvestris  that  as  resin  increases  in  the  stem  tannin  dimin- 
ishes in  like  proportion,  and  that  the  cells  surrounding  the 
resin  ducts  invariably  show  its  presence.  Hartig  suggests 
that  tannin  remains  in  the  oak  through  the  winter  in  the 
form  of  grains  similar  to  starch  grains,  but  distinguishable 
from  the  latter  by  characteristic  reactions.  These  grains, 
he  says,  are  dissolved  and  utilised  in  the  spring.  In  his 
later  writings  Sachs  inclines  to  the  same  view ;  he  says 
that  besides  those  which  must  be  looked  upon  as  excreta  or 
bye-products,  some  of  the  tannins  of  the  oak  are  most  likely 
to  be  regarded  as  reserve  products,  on  account  of  their  origin 
and  disappearance  and  their  behaviour  generally  during  the 
growth  of  the  plant  (71). 

The  localisation  of  tannin  in  the  different  parts  of  the 
plant  does  not  give  us  much  assistance  in  determining  which 
of  these  views  has  most  to  support  it.  It  is  often  found  in 
special  sacs  in  the  midst  of  metabolic  tissues  ;  it  is  very 
frequently  found  in  epidermal  cells,  either  in  the  interior  or 
saturating  the  cell  wall  ;  it  is  extremely  prominent  in  bark. 
These  positions  certainly  suggest  that  it  is  of  but  little  value 
as  a  food-stuff;  on  the  other  hand  it  is  often  abundant  in 
assimilating  parenchyma  in  which  starch  formation  is  pro- 
ceeding. 

In  Hillhouse's  paper  (70)  already  alluded  to,  the  author 
describes  a  considerable  number  of  observations  he  made  to 
determine  whether  or  no  a  disappearance  or  diminution  of 
tannin  could  be  detected  in  the  spring,  and  if  so,  whether  it 
was  a  reasonable  conclusion  that  such  diminution  indicated 
a  utilisation  of  the  vanished  portion. 

He  investigated  a  large  number  of  trees  in  which  tannin 


70  SCIENCE  PROGRESS. 

is  present  in  greater  or  less  amount,  and  noted  the  changes 
in  the  amount  present  in  winter  and  in  spring  in  their  various 
tissues.  He  concludes  that  in  no  case  is  there  noticeable  a 
diminution  of  tannin  in  early  winter  as  starch  accumulates, 
and  there  is  no  sign  that  the  starch  is  formed  at  the  expense 
of  the  tannin.  When  growth  recommences  in  the  spring, 
instead  of  tannin  disappearing  from  the  older  tissues  it  makes 
its  appearance  in  quantity  depending  on  the  amount  of 
growth.  The  tissues  of  the  bud  are  commonly  crowded 
with  it.  Hillhouse's  experiments  proceeded  upon  three 
lines.  In  the  first  place  plants  or  parts  of  plants  rich  in 
tannin  were  made  to  grow  under  conditions  in  which  assim- 
ilation of  C02  was  impossible  ;  a  second  set  of  experi- 
ments consisted  of  germinating  in  darkness  seeds  containing 
tannin  ;  and  finally  corms  were  investigated  to  see  whether, 
as  their  nutritive  material  was  transported  to  the  newly- 
formed  corm  springing  from  them,  tannin  was  transferred 
together  with  the  starch. 

In  no  case  was  any  diminution  or  transference  found, 
except  in  the  case  of  Pinus  sylvestris  already  alluded  to, 
when  the  probability  of  the  tannin  being  an  antecedent  of 
the  resin  became  evident. 

Those  tannins  which  are  undoubtedly  glucosides  must, 
however,  be  of  some  nutritive  value,  as  they  give  off  sugar 
on  decomposition  taking  place.  There  is  some  evidence  to 
show  that  during  the  ripening  of  certain  fruits  part  of  the 
sweetness  is  derived  from  an  astringent  principle  resembling 
and  probably  identical  with  tannin,  which  diminishes  in  quan- 
tity as  the  fruit  matures  (72). 

A  similar  uncertainty  as  to  its  physiological  meaning 
must  for  the  present  be  associated  with  phloroglucin  and 
the  compounds  into  which  it  enters,  which  are  to  be  re- 
garded as  ethers  corresponding  to  glucosides.  There  are 
two  classes  of  these  compounds,  which  have  been  described 
as  phoroglucides  and  phloroglucosides  respectively.  The 
former  include  such  bodies  as  hespentine,  phloretine,  etc., 
while  the  latter,  which  contain  a  sugar  group  in  their  for- 
mula, embrace  aurantine,  rhamnine,  hesperidine,  etc.  They 
are  somewhat  difficult  to  localise,  as  the  reactions  they  give 


THE  RESERVE  MATERIALS  OF  PLANTS.  71 

are  either  not  well  ascertained  or  not  particularly  distinctive. 
The  most  reliable  is  perhaps  that  with  vanilin  in  the  pre- 
sence of  hydrochloric  acid.  When  this  is  made  to  react 
upon  a  cell  which  contains  phloroglucin  in  the  sap,  the 
latter  forms  a  fine  precipitate  of  red  granules  which  are 
composed  of  a  compound  of  vanilin  and  phloroglucin,  known 
as  phloroglucivanilni. 

Phloroglucin  appears  to  be  often  present  in  the  plasma 
of  meristem  cells  rather  than  in  the  vacuole,  for  when  chlo- 
ride of  vanilin  is  added  to  a  tissue  containing  it  the  colouring 
mainly  affects  the  protoplasm,  some  of  the  vacuoles  remaining 
altosfether  uncoloured. 

The  distribution  of  phloroglucin,  like  that  of  tannin, 
leaves  a  good  deal  of  uncertainty  as  to  its  physiological 
meaning.  It  has  been  investigated  in  recent  years  by 
Waage  (73),  who  has  carefully  examined  representative 
plants  taken  from  almost  all  sections  of  the  vegetable 
kingdom.  Out  of  185  plants  submitted  to  experiment 
135  showed  it  to  be  present,  but  in  very  different  quan- 
tities. Of  the  135,  51  contained  a  very  considerable 
quantity,  41  less  but  still  a  tolerably  large  amount, 
while  in  43  though  present  only  a  feeble  reaction  could 
be  obtained.  Its  distribution  was  to  a  certain  extent 
regular,  for  the  author  states  that  if  one  species  contains 
it,  it  is  found  with  tolerable  certainty  in  all  the  species  of 
that  genus.  The  plants  of  the  Polypetalae  as  a  rule  show 
most,  while  the  Gamopetalae  and  the  Monocotyledons  are 
on  the  whole  poor  in  it ;  lower  down  in  the  scale  the  Vas- 
cular Cryptogams  and  the  Gymnosperms  are  charged  with 
it  to  a  degree  intermediate  between  the  other  groups. 

Examining  the  tissues  of  such  plants  as  contain  a  con- 
siderable quantity  it  may  be  found  in  meristems  and  in 
permanent  tissues.  In  axial  organs  it  occurs  in  the 
epidermis  and  later  in  the  bark  ;  also  in  the  parenchyma 
of  the  cortex,  and  in  the  sclerenchyma  of  the  tissues  more 
deeply  seated.  It  is  found  sometimes  in  the  endodermis  ; 
also  in  the  dead  cell  walls  of  the  xylem  parenchyma,  fibres, 
and  vessels.  The  medullary  rays  frequently  contain  a 
certain    quantity.       It    is    uniformly   absent  from    the    bast 


72  SCIENCE  PROGRESS. 

fibres  and  the  sieve  tubes,  and  may  be  present  or  not  in 
the  pith.  When  the  epidermis  contains  it,  it  is  usually 
in  the  hairs  if  any  are  present  ;  even  root-hairs  giving 
evidence  of  a  certain  amount.  Taking  the  members  of  the 
axis,  Waage  found  that  roots  as  a  rule  contain  more  than 
stems,  unless  the  latter  be  rhizomes,  in  which  it  is  fairly 
abundant.  Petioles  and  the  peduncles  of  flowers  contain 
less  than  branches.  In  plants  where  the  axis  is  highly 
charged  with  it,  there  is  generally  a  quantity  also  recog- 
nisable in  the  leaves,  chiefly  occurring  there  at  the  edges 
near  the  endings  of  the  veins,  and  further  in  the  neighbour- 
hood of  the  vessels  of  the  latter.  The  palisade  tissue  of 
the  leaf  has  usually  more  than  the  spongy  mesophyll,  and 
the  upper  has  more  than  the  lower  epidermis.  The  seed 
as  a  rule  contains  but  little,  and  that  is  only  in  the  integu- 
ments. 

If  the  disposition  may  be  taken  as  any  indication  of 
its  being  a  reserve  material  at  all,  the  probability  is  that  its 
value  in  the  latter  sense  is  but  slight.  The  disposition  of 
varying  amounts  in  the  medullary  rays  and  its  frequent 
presence  in  the  cells  of  the  cambium  layer  point  possibly 
to  its  supplying  nutritive  material  for  the  latter.  On  the 
other  hand,  its  consistent  absence  from  all  parts  of  the  seed 
except  the  integuments  seems  to  indicate  that  storage  of 
nutriment  is  not  its  main  purpose.  It  may  be  that  its  value 
to  the  meristem  tissues  is  based  upon  its  easily  oxidisable 
character,  affording  energy  thereby,  rather  than  being  a 
reserve  substance.  Its  occurrence  in  the  leaves  in  the 
localities  named  suggests  a  formation  in  the  mesophyll  and 
a  subsequent  transport  to  the  axial  regions.  But  against 
the  view  of  its  value  in  metabolism  as  a  reserve  material 
we  have  the  statement  that  light  does  not  affect  its  forma- 
tion.  It  is  in  Waage's  opinion  found  in  the  cell-sap  as  a 
general  rule,  rather  than  in  either  protoplasm  or  choro- 
plastids.  It  seems  on  the  whole  to  be  a  product  of 
destructive  metabolism,  for  it  occurs  in  the  same  cells  as 
starch  and  sugar  and  may  be  derived  from  the  latter  by 
abstraction  of  three  molecules  of  water,  C6HI206  -  3  H20  = 
C6H6Q3.      It    seems    to    resemble    tannin    in   that  it    often 


THE  RESERVE  MATERIALS  OF  PLANTS.  73 

increases  with  the  greater  development  of  the  plant,  and  in 
being  frequently  plentiful  in  parts  that  are  thrown  off  from 
the  latter,  such  as  old  leaves,  the  coats  of  fruits,  seeds,  etc., 
and  in  regions  withdrawn  from  active  metabolism,  such  as 
bark  and  to  a  less  degree  epidermis.  In  a  further  paper 
Waage  and  Nickel  suggest  that  it  may  possibly  be  a  source 
of  tannin,  as  the  latter  is  generally  found  in  the  same 
parts  as  phloroglucin  (74).  Tannin  does  not  appear,  how- 
ever, to  give  rise  to  phloroglucin. 

Like  tannin,  therefore,  phloroglucin  appears  to  be  on  the 
whole  an  accessory  product  and  only  rarely  to  act  as  a 
reserve  material.  The  compounds  of  it  which  contain 
sugar,  i.e.,  the  phloroglucosides,  may  serve  as  such,  yielding 
sugar  on  their  decomposition. 

In  certain  cases  the  alkaloids  appear  to  serve  as  reserve 
materials,  though  their  value  in  this  direction  is  probably 
but  slight.  Many  seeds  which  contain  them  in  some  con- 
siderable quantity  lose  them  during  germination,  and  other 
bodies,  principally  amides,  replace  them  in  the  developing 
embryo  or  young  seedling.  This  is  especially  the  case  with 
the  seed  of  Lathyrus  Sativus,  an  Indian  species  which 
contains  sometimes  as  much  as  '5  per  cent,  of  its  dry 
weight  of  an  alkaloidal  product  known  as  viciine  (75). 

The  possibility  of  alkaloids  helping  in  such  cases  to 
form  albuminoid  materials  or  proteids  has  been  pointed  out 
by  Jorissen  (76)  in  his  discussion  of  the  chemical  processes 
incident  to  germination,  in  which  he  claims  for  them  a 
certain  value  as  reserve  materials.  Heckel  [jj)  comes  to 
the  same  conclusion.  He  carried  out  experiments  with 
Sterculia  acuminata,  Strychnos  Nux-vomica,  Physostigma 
venenostim,  and  Datura  Stramonium,  and  found  in  all  these 
cases  that  during  germination  the  greater  part  of  their 
alkaloidal  principles  disappears.  He  claims  that  this 
disappearance  is  due  to  a  transformation  into  assimilable 
substances  under  the  influence  of  the  embryo.  If  the 
latter  be  extracted  from  the  seeds,  and  they  be  then  sur- 
rounded by  or  buried  in  moist  earth,  the  alkaloids  remain 
for  a  considerable  time  unchanged. 

The  conclusions  of  Jorissen  and  Heckel  are  disputed  by 


74  SCIENCE  PROGRESS. 

Clautriau  (78),  who  finds  another  explanation  of  the  dis- 
appearance of  the  alkaloids  during  germination  in  a  possible 
destruction  of  them  as  deleterious  bodies  which  would 
affect  prejudicially  the  development  of  the  young  seedling. 
He  has  ascertained  with  considerable  precision  the  dis- 
tribution of  the  alkaloid  in  the  seeds  of  Atropa  Beliadona, 
Datura  Stramonium,  and  Hyoscyamus  Niger,  and  states 
that  it  is  confined  entirely  to  a  layer  of  cells  situated 
between  the  albumen  and  the  integument  of  the  seed,  which 
when  the  latter  is  mature  is  very  much  reduced  in  its 
dimensions.  This  layer  is  much  more  prominent  while  the 
seed  is  ripening,  consisting  of  many  cells  with  very  rich 
contents,  the  latter  consisting  of  starch  and  albuminoid  sub- 
stances as  well  as  alkaloids.  As  the  albumen  grows,  this 
nourishing  layer  gradually  yields  up  both  starch  and  pro- 
teids,  while  the  alkaloid  persists  ;  the  cells  become 
gradually  nearly  empty,  and  dry  up  considerably,  ultimately 
becoming  dead.  In  this  condition  they  still  contain  the 
alkaloid,  the  quantity  of  which  does  not  diminish  during  the 
changes  described.  When  the  seed  is  mature,  this  layer 
is  very  thin,  the  cells  being  flattened  and  compressed  to- 
gether, forming  a  sort  of  membrane  in  which  the  alkaloids 
remain,  partially  or  wholly  combined  with  an  organic  acid. 

The  nutritive  value  of  the  alkaloid  seems  improbable 
when  we  consider  the  disappearance  from  this  layer  of  the 
starch  and  proteids,  and  the  retention  of  the  former.  If  it 
were  then  a  reserve  product  it  would  in  all  probability  ac- 
company the  other  undoubted  nutritive  bodies.  Clautriau 
has  obtained  further  information  on  this  point  by  depriving 
seeds  of  Datura  Stramonium  of  this  alkaloidal  layer  and 
submitting  them  to  germination,  either  in  moist  earth  or  in 
an  atmosphere  saturated  with  watery  vapour.  He  found 
that  under  such  conditions  they  germinated  normally,  and 
produced  young  seedlings  which  differed  in  no  particulars 
from  normal  seedlings  of  Datura. 

Clautriau  extended  his  researches  to  other  plants  than 
those  named,  particularly  Conium  maculatum,  from  which 
he  obtained  the  same  results. 

Examining   the     young   seedlings   grown    under    these 


THE  RESERVE  MATERIALS  OF  PLANTS.  75 

conditions,  no  alkaloid  being  allowed  to  remain  in  the  seed, 
Clautriau  found  that  the  active  principle  made  its  appear- 
ance in  considerable  quantity,  and  chiefly  in  thegrowingapices. 
The  same  thing  was  noticeable  in  the  development  of  mor- 
phine in  the  poppy  (79),  where  a  more  gradual  formation 
was  detected.  Morphine  does  not  show  itself  at  the  out- 
set of  the  development  of  the  plant,  but  appears  to  be 
preceded  by  another  alkaloid,  giving  very  clear  reactions, 
which  does  not  seem  to  be  identical  with  any  of  the  nitro- 
genous principles  extracted  from  opium. 

The  conclusion  that  must  be  drawn  from  these  investiga- 
tions is  that  these  alkaloids,  and  hence  probably  all  such  bodies, 
are  not  to  be  regarded  as  reserve  materials,  but  as  bye- 
products  or  excreta,  appearing  coincidently  with  the  active 
metabolic  processes  of  the  growing  plant. 

Besides  these  accumulations  of  more  or  less  complex 
organic  compounds  in  the  tissues  of  plants  we  meet  with 
certain  cases  where  inorganic  material  is  deposited  with  a 
view  to  subsequent  utilisation.  These  are,  however,  of 
much  less  importance  and  only  occur  in  comparatively  few 
plants.  We  have  the  well-known  globoids  in  the  aleurone 
grains  of  the  castor-oil  seeds,  the  seeds  of  Bertholletia 
excelsa  and  several  others.  From  their  disposition  and 
fate,  and  from  the  fact  that  they  afford  a  supply  of  phos- 
phorus, it  is  probable  that  we  may  include  them  in  this 
group.  In  certain  cases  also  the  collections  of  crystals  of 
calcium  oxalate  gradually  disappear  from  the  cells  in  which 
they  are  deposited,  and  so  seem  to  minister  to  the  needs  of 
the  plant  for  calcium,  an  element  whose  function,  however, 
is  still  practically  unknown. 

BIBLIOGRAPHY. 

(60)  Thome.      Ueber  das  Verkommen  des  Amygdalins  und  des 

Emulsins  in  den  bittern   Mandeln.     Botanische  Zeitung,   p. 
240,  1865. 

(61)  PORTES.     Recherches  sur  les  amandes    ameres.     Journal  de 

pharmacie  et  de  chimie,  t.  xxvi.,  p.  410,  1877. 

(62)  PFEFFER.     Pflanzenpkysiologie,  t.  i.,  p.  307,  1881. 

(63)  JOHANSEN.     Sur  la  localisation  de  l'emulsine  dans  les  aman- 

des.    Ann.  des.  Sc.  Nat.  Bot.,  7  ser.,  t.  vi.,  p.  118,  1887. 


76  SCIENCE  PROGRESS. 

(64)  GuiGNARD.       Sur    la    localisation,    dans    les    amandes    et    le 

Laurier-cerise,  des  principes  qui  fournissent  l'acide  cyan- 
hydrique.  Journal  de  pharmacie  et  de  chimie,  5  ser.,  t.  xxi., 
pp.  233-289,  1890. 

(65)  Treub.     Sur  la  localisation,  le  transport,  et  le  role  de  l'acide 

cyanhydrique    dans    le    Pangium    edule    Reinw.      Ann.  du 
Jardin  Botanique  de  Buitenzorg,  xiii.,  p.  189,  1895. 

(66)  GuiGNARD.       Recherches    sur    la    localisation    des    principes 

actifs  des  Cruciferes.    Journal  de  Botanique  (March),  1890. 

(67)  GuiGNARD.     Recherches  sur   la   nature  et  la  localisation  des 

principes  actifs  chez  les  Capparidees,  Tropeolees,  Limnan- 
thees,   Resedacees,   et   Papayacees.      Journal  de  Botanique, 

1893- 

(68)  SACHS.       Ueber   die     Keimung    von    Phaseolus    multiflorus. 

Sits,  der  Wien  Akad.,  1859. 

(69)  Schell.     Physiologische  Rolle  der  Gerbsaure.     Bot.  Jalires- 

berlcht,  1875. 

(70)  HlLLHOUSE.    Some  Investigations  into  the  Function  of  Tannin 

in  the  Vegetable  Kingdom.     Midland  Naturalist,  1887-8. 

(71)  SACHS.      Vorlesungen  iiber  PJlanzenphysiologie,  1882. 

(72)  BuiGNET.     Ann.  Chemie  Phys.,  ser.  iii.,  Bd.  61,  1861. 

(73)  Waage.     Ueber  das  Vorkommen  und  die  Rolle  des  Phloro- 

glucins  in  der  Pflanze.  Ber.  d.  dent.  bot.  Gesell.,  November, 
1890. 

(74)  Waage  and  NICKEL.     Zur  Physiologie  des  Geitstoffs  und  der 

Trioxybenzol.     Bot.  Central.,  1891. 

(75)  RlTTHAUSEN.    Journ.  Jur  pract.  Chem.,  new  series,  vol.  xxiv., 

p.  202,  1 88 1. 
(j6)  JORISSEN.       Les    phenomenes   chimiques   de   la   germination. 
Memoires  couronncs  de  I' Acad.  Royale  de  Belgique,  lxxxviii., 

P-  73- 

(77)  HECKEL.     Sur  l'utilisation  et  les  transformations  de  quelques 

alcaloi'des  dans  la  graine  pendant  la  germination.  Comptes 
Rendus,  January,  1891. 

(78)  Clautriau.     Localisation  et  signification  des  alcaloides  dans 

quelques  graines.  Ann.  de  la  Societe  beige  de  Microscopie 
{Memoires),  t.  xviii.,  1894. 

(79)  CLAUTRIAU.      Recherches  microchimiques  sur  la  localisation 

des  alcaloi'des  dans  le  Papaver  somniferum.  Mem.  de  la  Soc. 
beige  de  Microscopie,  t.  xii. 

J.   Reynolds  Green. 


jj  L  I  »  &  A  R  Yj  3u 

AFRICAN    GRASS    FIRES    AND   THEIR^     m     +   £V 

EFFECTS.  N&  V  >^ 

MANY  parts  of  the  interior  of  tropical  Africa  consist 
of  wide  grassy  plains,  occasionally  varied  by 
scattered  trees,  but  usually  very  bare  and  monotonous  in 
appearance.  In  the  rainy  season  these  steppes  are  green 
with  vigorously  growing  grass,  and  patrolled  by  hundreds 
of  antelopes  and  other  kinds  of  game  ;  a  few  months  after- 
wards when  the  rains  are  over,  they  are  covered  by 
blackened  ashes  and  charcoal,  and  not  a  living  creature  will 
be  visible  except  perhaps  a  few  birds  or  a  very  occasional 
ground-rat. 

These  fires  are  usually  due  to  the  natives,  who  find 
that  the  bush  can  be  most  easily  cleared  by  their  assistance, 
though  they  are  often  lighted  to  satisfy  the  childish  delight 
in  a  big  blaze  which  is  characteristic  of  the  Suahili  porter. 

Their  effects  are  most  interesting,  both  economically 
and  also  in  the  way  in  which  they  entirely  change  the 
aspect  of  the  vegetation. 

It  is,  of  course,  immediately  obvious  that  all  the  valu- 
able feeding  material  of  many  square  miles  of  luxuriant 
grass  is  by  these  fires  entirely  wasted  ;  but,  besides  this, 
the  soil  is  never  permitted  to  grow  rich  through  the 
accumulation  of  leaf-mould  and  stems,  and  in  fact  the  land 
is  every  year  brought  back  into  exactly  the  same  condition. 
No  true  turf  is  formed,  and  the  soil  remains  more  like  the 
subsoil  in  cultivated  countries  and  never  becomes  in  the 
least  improved. 

The  effect  on  the  vegetation  is  very  curious.  The 
season  of  flowering  for  many  trees  and  herbaceous 
plants  is  completely  altered.  A  large  number  of  low- 
growing  herbaceous  plants  possess  woody  root-stocks  or 
some  sort  of  underground  store  of  nourishment.  With  the 
very  first  shower  of  the  rainy  season,  these  stores  send  up 
flowering  stems  entirely  without  leaves,  and  the  bare  and 
blackened  earth  is  studded  with  the  bright  purple  flowers  of 


78  SCIENCE  PROGRESS. 

Dolichos  spp.,  the  blue  Pentanisia  Schweinfurthii,  little 
white  Euphorbias,  Lasiosiphon  spp.,  etc.  These  all  have 
the  appearance  of  a  flower  cut  off  and  planted  in  the  earth, 
and  give  rise  to  remarks  on  the  collector's  carelessness  in 
not  bringing  leaves  when  worked  up  by  untravelled 
botanists.  With  the  setting  in  of  the  rains,  the  stems 
begin  to  grow  and  produce  leaves  until,  when  the  grass  has 
sprung  up,  all  these  herbs  are  in  full  foliage.  This  habit  is 
of  great  advantage  to  the  flowers  concerned,  as  insects 
can  readily  perceive  the  scattered  flowers  which  in  the  grass 
would  be  quite  inconspicuous.  The  same  thing  occurs  in 
many  of  the  trees.  Several  species  of  Dombeya,  for  example, 
send  out  their  flowers  at  this  foreshadowing-  of  the  rains 
and  are  most  conspicuous. 

Another  curious  effect  of  the  fires  is  the  manner  in 
which  trees  are  either  kept  down  or  obliged  to  protect 
themselves  in  some  way  against  their  action.  In  the  more 
arid  plains  trees  seldom  exist,  or  if  present  occur  in  the 
form  of  stumps  perhaps  ten  years  old,  but  never  able  to 
grow  higher  than  a  foot  or  so.  Such  stumps  put  out  every 
wet  season  vigorous  shoots,  which  are  annually  burnt  away 
and  only  the  short  stem  with  another  layer  of  wood  is  left 
to  survive. 

Of  the  trees  which  do  manage  to  exist  in  spite  of  the 
annual  conflagration,  the  most  remarkable  are  the  tree 
Euphorbias,  often  twenty  to  twenty-five  feet  high.  These 
have  angular  fleshy  branches  protected  by  a  leathery 
epidermis,  and  besides  their  milky  juice,  which  contains 
gum,  caoutchouc  and  other  substances,  have  a  large  amount 
of  mucilage  or  slimy  matter  in  the  ordinary  tissue.  This 
latter  is  a  strongly  waterholding  substance,  and  the  most 
violent  fire  seems  unable  to  do  more  than  scorch  a  very  few 
of  the  outermost  branches. 

It  is  a  most  curious  fact  that  though  when  living  they 
resist  fires  in  this  wonderful  manner,  dead  branches  make 
an  excellent  fire  and  blaze  up  most  vigorously.  I  cannot 
understand  this  difference. 

Of  the  other  trees  which  continue  to  thrive  in  these 
places,  there  are  some  seven  species  which  grow  in  abun- 


AFRICAN  GRASS  FIRES  AND  THEIR  EFFECTS.    79 

dance  ;  there  will  be  usually  500  of  one  of  these  species  to 
every  individual  of  some  other  kind.  I  brought  home 
specimens  of  the  bark  of  these  six  or  seven  forms,  which 
were  given  to  Professor  Bretland  Farmer  for  examination, 
who  replied  as  follows  :  "  I  examined  your  specimens  of 
bark  and  they  all  agree  in  possessing  cells  which  show  a 
certain  amount  of  gummy  degeneration  of  the  cells  in  the 
bark,  together  with  the  presence  of  a  considerable  amount 
of  sclerotic  cells  ;  it  seems  not  impossible  that  these  two 
facts  may  be  connected  with  the  resistance  of  the  plants  to 
the  fires,  and  I  found  as  a  matter  of  fact  that,  on  comparing 
the  rate  of  burning  of  these  barks  with  that  of  laburnum, 
they  were  very  slowly  consumed. 

"  I  should  have  added  that  there  are  repeated  periderms, 
and  intermixed  with  the  cork  are  the  sclerotic  cells 
already  mentioned."  Now  the  artificially  produced  cork 
of  commerce  shows  great  similarity  in  some  respects  to 
the  cork  of  these  fireproof  trees.  The  process  adopted 
both  with  the  birch  and  the  cork  oak  is  to  carefully  peel  off 
the  cracked  superficial  layer  of  bark  or  "  male  cork  "  (this  is 
known  as  "demasclage").  After  this  the  layer  of  cork 
increases  enormously  and  may  perhaps  attain  to  17  cm. 
in  thickness  if  left  untouched  :  the  result  is  the  ordinary 
commercial  article.  I  do  not  think  that  it  is  going  too  far 
to  say  that  we  have  in  grass  fires  a  natural  "  demasclage  " 
process,  for  they  will  certainly  destroy  the  outer  more  or 
less  dead  tissues. 

From  the  researches  of  Henslow,1  Tschirch2  and 
Volkens 3  on  desert  plants,  it  may  be  considered  proved 
that  cutin,  which  most  modern  authorities  consider  nearly 
identical  with  suberin,  is  directly  increased  by  dry  and  arid 
conditions,  so  that  this  direct  effect  is  probably  also  of 
use  in  increasing  the  deposition  of  corky  matter.  Both 
evils — -the  fire  and  the  drought — have,  as  so  often  happens, 
brought  about  their  own  remedy.  The  sclerotic  cells  (or  stone 
cork  ?)  may  doubtfully  be  set  down  to  the  same  cause,  for 

1  Origin  of  Plant  Structures. 

2  Angewandte  Anatomie  and  Linnea,  1881. 

3  Flora  der  egypt.  arab.  IVuste. 


80  SCIENCE  PROGRESS. 

culture  experiments  (Duchartre  and  Henslow,  loc.  cit.,  p.  57) 
show  that  sclerenchyma  may  be  directly  diminished  by  a 
more  moist  atmosphere. 

The  occurrence  of  gum  is  not  so  clearly  dependent  on 
the  climatic  conditions  ;  its  use  in  these  forms  is,  however, 
obvious  enough,  for  all  apertures  by  which  water  might  be 
lost  are,  so  to  speak,  gummed  up.  This  is  quite  similar  in 
physiological  action  to  the  drops  of  mucilage  or  gum  which 
hermetically  seal  the  vessels  exposed  by  cutting  across  a 
branch  of  any  ordinary  deciduous  tree. 

It  is  true  that  the  production  of  gum  is  known  to  be 
most  abundant  in  a  dry  and  hot  season,  but  according  to 
the  explanation  given  by  Tschirch,  loc.  cit.,  p.  2  1 1  (and  an 
identical  account  has  been  given  me  by  Mr.  Malcolm  Dunn 
as  the  result  of  experience),  this  is  due  to  the  gum  being 
squeezed  out  by  the  contraction  of  the  bark  following  on  a 
wet  period,  during  which  the  masses  of  gum  in  the  bark 
are  greatly  swollen.  I  cannot  find  any  explanation  of  the 
actual  cause  of  the  change  of  cellulose  into  gum,  but  Mr. 
Malcolm  Dunn  states  the  general  opinion  that  it  is  abundant 
after  a  severe  shaking  of  the  trees,  as,  for  example,  in  a  violent 
wind.  Such  places  as  those  here  treated  of  are  certainly 
exposed  to  wind  (otherwise  they  would  be  covered  by 
forest,  according,  that  is,  to  my  experience),  and  it  is  possible 
that  the  wind  may  have  assisted  in  starting  gum  formation  ; 
but  if,  as  is  not  unlikely,  the  wind  acts  indirectly  by  straining 
the  layers  of  the  cell  walls,  it  seems  more  probable  that  the 
fierce  heat  of  the  fire,  causing  sudden  and  violent  shrinking 
and  warping  of  the  bark,  strains  the  cell  walls  in  the  same 
manner.  This  may  of  course  be  quite  unproved,  but  the 
facts  are  sufficiently  interesting  to  justify  further  research. 

G.   F.  Scott  Elliot. 


Bcimce  progress. 


No.  26.  April,   1896.  Vol.  V. 


THE    GENERAL    BEARINGS    OF    MAGNETIC 

OBSERVATIONS. 

IF  necessity  be  the  surest  prompter  of  invention,  it  is  not 
too  much  to  say  that  the  necessity  of  the  navigator 
has  been  a  most  potent  factor  in  producing  the  observer  of 
the  elements  of  Terrestrial  Magnetism.  The  traveller  on 
land  might  rest  during  darkness  until  daylight  enabled  him 
to  resume  his  journey  ;  but  the  seaman  on  the  trackless 
ocean  was  dependent  upon  the  indications  of  his  compass 
by  day  and  night ;  and  after  the  discovery  of  Columbus 
that  the  magnetic  Declination  or  Variation  of  the  needle 
from  the  direction  of  the  geographical  North  varied  in 
amount  with  the  Latitude  and  Longitude,  a  new  impetus 
was  given  to  observation. 

The  publication  of  Gilbert's  grand  discovery  that  the 
earth  is  a  magnet  and  the  director  of  the  freely  suspended 
needle,  followed  by  the  discovery  of  the  secular  change  in 
the  value  of  the  Declination,  naturally  added  to  the  desire 
of  both  landsmen  and  seamen  to  know  as  much  as  possible 
concerning  that  great  magnet,  both  from  purely  scientific 
reasons  and  to  meet  the  practical  ends  of  the  navigator. 
Thus  the  seventeenth  and  eighteenth  centuries  were  re- 
markable for  the  number  of  observers  both  of  the  magnetic 
Dip  and  Declination. 

So  important  had  a  correct  knowledge  of  the  Declination 

become  to  the  requirements  of  navigation,  as  early  as  the 

close  of  the  seventeenth  century,   that   Halley,   under  the 

6 


82  SCIENCE  PROGRESS. 

immediate  auspices  of  the  Government,  made  his  celebrated 
voyage  over  the  Atlantic  Oceans  in  a  man-of-war,  in  order 
that  intelligent  observation  should  set  at  rest  much  that  was 
doubtful.  The  results  of  this  voyage,  combined  with  the 
observations  of  previous  navigators,  were  embodied  in  his 
celebrated  chart  of  lines  of  equal  value  of  magnetic  Varia- 
tion or  Declination,  the  first  of  its  kind  and  of  so  convenient 
a  form  that  charts  of  equal  values  of  the  three  magnetic 
elements  are  to  this  day  the  most  acceptable  form  for 
representing  the  combined  results  of  magnetic  observations 
made  over  large  areas  of  sea  and  land,  as  well  as  of  the 
special  magnetic  surveys  which  in  recent  years  have  been 
made  in  various  countries. 

Here  we  may  pause  to  consider  the  word  Declination  as 
applied  to  the  angle  which  the  direction  of  the  horizontal 
magnetic  needle  makes  with  the  true  meridian.  Many 
magneticians  object  to  the  word,  but  no  better  has  yet  been 
proposed  or  at  any  rate  accepted  ;  the  result  being  that 
while  observers  on  land  use  the  term,  seamen  adhere  firmly 
to  the  expression  "Variation  of  the  Compass".  This  is  as 
might  be  expected  when  it  is  remembered  that  navigators 
look  upon  the  word  Declination  as  connected  with  the  posi- 
tion of  the  sun  and  other  heavenly  bodies,  and  would  find  it 
most  inconvenient  to  have  the  same  word  in  daily  use, 
meaning  two  totally  different  things. 

During  the  eighteenth  century  charts  of  the  magnetic 
Declination  were  published  by  Mountaine  and  Dodson, 
Bellin,  and  Churchman,  and  for  their  time  may  be  con- 
sidered as  fair  approximations  to  the  truth.  Churchman's 
design  was  not  only  to  give  values  of  the  Declination  but 
to  furnish  the  seaman  with  a  means  of  ascertaining  the 
Longitude,  an  ambitious  project,  especially  as  we  now 
know  there  were  probably  considerable  elements  of  error 
in  these  charts  caused  by  local  magnetic  disturbance  of  the 
observing  compass  on  land,  and  from  the  iron  used  in  con- 
struction disturbing  the  compass  on  board  the  ships. 

This  latter  source  of  error  was  only  beginning  to  be 
viewed  in  its  true  light  at  the  close  of  the  eighteenth 
century. 


THE  BEARINGS  OF  MAGNETIC  OBSERVATIONS.     83 

In  the  years  1801-2  Commander  Flinders  of  H.M.S. 
Investigator,  then  surveying  the  southern  coasts  of  Australia, 
found  that  when  his  vessel's  head  was  north  or  south  by 
compass  the  observed  Declination  agreed  very  nearly,  but 
when  she  lay  with  her  head  east  or  west,  it  differed  largely. 
Moreover  these  errors  on  the  east  and  west  points  of  the 
compass  had  the  opposite  sign  to  those  observed  in  Eng- 
land. 

Flinders,  however,  had  supplemented  the  existing 
scanty  knowledge  of  the  distribution  of  the  Dip  over 
navigable  waters  by  several  observations  of  his  own  in 
northern  and  southern  latitudes,  and  from  these  he  drew 
the  conclusion  that  the  errors  in  the  Declination  observed 
on  board  ship  were  caused  by  magnetism  induced  by  the 
earth  in  the  vertical  iron  of  the  ship,  and  changed  in  value 
proportionally  to  change  of  Dip.  Here  Flinders  was  wrong, 
as  the  errors  were  really  proportional  to  the  tangent  of  the 
Dip. 

In  spite  of  this  mistake  he  was  enabled  from  his  know- 
ledge of  the  Dip  to  conceive  the  idea  of  so  placing  vertical 
bars  of  iron  that  they  produced  an  equal  and  opposite  effect 
on  the  compass  to  that  of  the  ship  in  all  latitudes,  and  thus 
invented  what  is  now  called  the  Flinders  bar,  one  of  the 
most  important  correctors  of  compass  disturbance  in  the 
iron  and  steel  ships  of  the  present  day. 

In  1 8 14  Flinders  induced  the  Admiralty  to  have  ex- 
periments made  on  board  men-of-war  at  Portsmouth, 
Sheerness,  and  Devonport,  to  ascertain  the  amount  of  the 
magnetic  disturbance  of  the  compass  caused  by  the  iron  in 
each  ship.  The  chief  reason  for  making  these  experiments 
was  to  show  the  necessity  for  ascertaining  and  applying 
these  errors  to  ensure  the  safe  navigation  of  the  ships,  but 
it  had  also  a  direct  bearing  in  enabling  observers  to  elimi- 
nate the  hitherto  inexplicable  divergencies  in  the  values  of 
the  Declination  observed  in  different  ships  in  the  same 
geographical  position.  The  results  of  these  experiments 
bore  no  immediate  fruit,  for  with  the  death  of  Flinders  the 
subject  was  temporarily  neglected. 

In  1 8 19,  Hansteen  published  his  Magnetismus  der  Erde 


84  SCIENCE  PROGRESS. 

with  an  atlas  containing  charts  of  the  elements  Declination 
and  Dip  for  different  epochs  between  the  years  1600  and 
1787.  These  charts  were  in  a  large  measure  compiled  from 
observations  made  with  imperfect  instruments  and  subject 
to  the  causes  of  error  already  mentioned  attending  both  land 
and  sea  results.  Hansteen,  however,  considered  them  of 
sufficient  value  to  enable  him  to  draw  certain  important  con- 
clusions with  regard  to  the  cause  of  the  secular  change  of 
the  magnetic  elements.  Thus  he  not  only  concurred  with 
Halley  that  the  earth  considered  as  a  magnet  had  four 
poles  or  points  of  attraction,  but  computed  their  geo- 
graphical positions.  Further  than  this,  he  computed  that 
to  account  for  the  secular  change  these  four  supposed 
poles  revolved  round  the  terrestrial  poles,  each  pole 
occupying  a  widely  different  number  of  years  to  complete 
the  revolution. 

If  these  theoretical  results  had  been  true,  a  great 
advance  would  have  been  made  not  only  in  the  science 
of  terrestrial  magnetism  but  in  its  practical  bearing  on  the 
requirements  of  the  present  day. 

Although  Humboldt  had  about  the  year  1800  shown 
that  the  intensity  of  the  earth's  magnetism  varied  with  the 
latitude,  the  general  distribution  of  that  magnetic  element 
was  so  little  known  that  we  may  with  our  present  extended 
knowledge  consider  that  Hansteen's  conclusions  were  based 
on  insufficient  data.  In  fact  the  idea  of  the  earth  being  a 
magnet  with  four  poles  has  long  since  been  abandoned  in 
favour  of  there  being  one  pole  with  two  foci  of  intensity  in 
each  hemisphere,  and  reasons  will  be  given  further  on 
which  tend  to  throw  doubt  on  there  being  any  revolution  of 
these  two  magnetic  poles  round  their  adjacent  terrestrial 
poles. 

Subsequently  to  Hansteen's  charts  there  appeared  those 
of  the  Declination  by  Yeates,  Duperrey,  and  by  Barlow  in 
1836.  These  were  useful  to  navigation  but  helped  very 
little  towards  the  solution  of  the  problem  of  the  ever  vari- 
able distribution  of  the  earth's  magnetism. 

Besides  this  by  the  year  1835  the  iron-built  ship  had 
appeared   on  the    ocean  and  a  correct    knowledge   of  the 


THE  BEARINGS  OF  MAGNETIC  OBSERVATIONS.     85 

three  magnetic  elements  became  a  necessity  in  solving  the 
problems  which  the  magnetism  of  different  iron  ships 
presented. 

With  Gauss's  invention  of  the  absolute  horizontal  force 
magnetometer  in  1833,  many  hitherto  unknown  move- 
ments of  the  magnetic  needle  of  the  highest  interest  were 
discovered,  which  with  the  coarser  instruments  previously 
in  use  lay  concealed.  This  discovery  gave  the  desired 
impetus  to  the  scientific  men  of  that  epoch,  and  the  period 
included  in  the  years  1835-45  was  "a  time  of  unparalleled 
activity  in  the  extension  of  systematic  and  accurate  mag- 
netical  observations  over  the  earth's  surface  ". 

Whilst  most  of  the  continental  nations  joined  in  this 
movement,  the  principal  share  in  the  work  was  divided 
between  Germany,  Russia,  and  England  in  Europe,  and  the 
United  States  in  America.  But  before  the  splendid  series 
of  simultaneous  observations  made  on  the  continent,  and 
four  British  colonial  observatories  were  organised,  Gauss 
in  1839  published  his  general  theory  of  Terrestrial  Magnetism 
coupled  with  a  series  of  charts  of  the  three  magnetic  elements 
for  the  whole  world,  based  upon  observations  made  at 
ninety-two  selected  stations  distributed  over  the  earth's 
surface  ;  and  it  may  be  remarked  that  Gauss's  charts  not 
only  gave  results  in  fair  accordance  with  observation  in 
explored  regions,  but  also  as  afterwards  proved  in  Antarctic 
latitudes  hitherto  unvisited  by  man. 

The  proof  came  in  the  years  1839-43,  when  Ross's 
Antarctic  voyage  of  exploration  was  carried  out  in  the 
interests  of  terrestrial  magnetism.  Besides  the  importance 
of  a  knowledge  of  the  general  distribution  of  the  magnetic 
elements  in  those  regions,  one  great  aim  of  this  expedition 
was  to  reach  the  south  magnetic  pole.  This  was  found  to 
be  impossible,  but  sufficient  data  were  collected  to  give  its 
approximate  position.  Whilst  this  Antarctic  magnetic 
survey  was  being  completed,  that  of  British  North 
America  was  also  undertaken  with  the  result  of  the  deter- 
mination of  the  locality  of  one  of  the  foci  of  greatest 
intensity  in  the  northern  hemisphere. 

The  results  of  these  surveys  formed,   as  will   be  well 


86  SCIENCE  PROGRESS. 

remembered,  a  valuable  series  of  "contributions"  to  terres- 
trial magnetism  by  Sabine,  and,  coupled  with  every  available 
observation  between  the  years  1818  to  1876,  formed  the 
materials  for  the  series  of  charts  entitled  "  The  Magnetic 
Survey  of  the  Globe "  for  the  epoch  1842*5.  Each  map 
gave  normal  lines  of  equal  values  of  the  Declination,  In- 
clination and  Intensity.  Although  it  may  be  said  that  from 
the  Arctic  circle  to  the  Antarctic,  the  direction  of  the  lines 
was  efficiently  given  by  observation,  the  lines  within  those 
circles  were  largely  taken  from  Gauss's  computed  lines 
modified  to  agree  with  observation. 

Another  difficulty  in  compiling  these  charts  of  Sabine's 
with  accuracy  lay  in  the  uncertain  knowledge  of  the  secular 
change  then  available,  and  which  had  to  be  applied  to 
observations  made  so  far  apart  in  time. 

Sabine's  charts  are  doubtless  the  best  we  have  for  the 
epoch  1842*5,  but  in  the  light  of  the  requirements  of 
modern  science  they  leave  much  to  be  desired  as  regards 
the  Antarctic  regions.  The  observations  south  of  6o°  S. 
were  made  entirely  on  board  ships,  where  the  errors  of  the 
compass  sometimes  exceeded  50°  due  to  the  horizontal 
forces  in  the  ship,  thus  rendering  accurate  observations  of 
the  Declination  very  uncertain  and  correction  of  the  observed 
Inclination  very  difficult  ;  besides  which  there  are  no 
records  of  the  ship's  disturbing  force  in  the  vertical  direc- 
tion. 

Naval  requirements,  however,  did  not  permit  of  any 
delay  in  publishing  magnetic  charts  affecting  navigation, 
for  in  1846  the  Hydrographer  of  the  Admiralty  requested 
Sabine  to  provide  charts  of  the  Declination  for  the  Atlantic 
Oceans  from  6o°  N.  to  6o°  S.  These  were  largely  used  until 
Evans's  chart  of  the  Declination  for  the  whole  navigable 
world  was  issued  in  1858. 

The  excellent  work  of  Flinders  already  referred  to,  of 
ascertaining  from  his  knowledge  of  terrestrial  magnetism 
the  chief  cause  of  the  deviation  of  the  compass  in  wood- 
built  ships,  and  providing  a  corrector  for  those  deviations, 
had  to  be  followed  up  on  a  much  larger  scale  and  with 
more  exact  methods  in   the   iron-built   ship,   which,  in  that 


THE  BEARINGS  OF  MAGNETIC  OBSERVATIONS.     87 

period  of  activity  in  terrestrial  magnetic  science — 1835-45 — 
was  rapidly  increasing  in  numbers  on  the  ocean. 

Thus  in  1835  observations  were  made  on  board  iron 
ships  showing  that  they  acted  as  a  magnet  on  their  com- 
passes, but  there  was  nothing  to  show  in  the  results  what 
the  causes  of  this  condition  of  the  iron  ship  were,  until 
Poisson  in  1838  published  his  celebrated  "Memoir  on  the 
deviations  of  the  compass  produced  by  the  iron  in  a  ship  ". 
This  was  a  rigorous  mathematical  investigation  of  the 
subject,  showing  that  the  deviations  of  the  compass  were 
due  to  induction  in  the  ship  by  the  magnetic  force  of  the 
earth. 

If  the  iron  ship  had  simply  been  built  for  service  in  one 
locality,  a  limited  knowledge  of  terrestrial  magnetism  would 
have  sufficed  to  elucidate  the  causes  of  her  magnetic  con- 
dition ;  but  she  was  destined  to  traverse  every  navigable 
sea  over  large  changes  of  magnetic  latitude,  hence  the 
necessity  for  an  accurate  knowledge  of  the  distribution  of 
magnetism  over  the  great  parent  magnet,  in  order  to 
determine  the  magnetic  condition  of  her  comparatively 
minute  offspring  the  magnetised  iron  ship  ;  and  this  at  all 
times  and  in  all  places  in  the  interests  of  navigation. 
Observations  of  the  terrestrial  magnetic  elements  were 
therefore  an  absolute  necessity  if  iron-built  ships  were  to  be 
substituted  for  those  of  wood. 

The  ability  to  predict  the  deviation  of  the  compass  on 
change  of  latitude  did  not,  however,  satisfy  Airy,  for  after 
a  remarkable  mathematical  investigation  of  iron  ship's 
magnetism  of  a  less  rigorous  character  than  Poisson's,  but 
sufficiently  accurate  for  his  purpose,  he  in  1839  proposed 
his  methods  of  annulling  the  deviation  of  a  ship's  compass 
by  means  of  magnets  and  soft  iron,  so  arranged  as  to  pro- 
duce equal  and  opposite  magnetic  effects  to  that  of  the 
ship.  Provided  with  Airy's  admirable  and  simple  directions 
this  method  of  correction  was  comparatively  easy  in  one 
latitude,  but  experience  at  sea,  especially  in  voyages  to  the 
Cape  of  Good  Hope,  showed  that  every  iron  ship  required 
a  different  application  of  Airy's  correctors. 

To  discriminate  between   the  amount   that   was   to   be 


88  SCIENCE  PROGRESS. 

corrected  by  permanent  magnets,  by  horizontal  soft  iron, 
and  by  vertical  soft  iron,  an  accurate  knowledge  of  the 
magnetic  elements  Dip  and  Intensity  obtained  from  obser- 
vations on  land  and  at  sea  was  essential. 

Before  dismissing  the  subject  of  the  above  application 
of  magnetic  observations,  it  may  be  remarked  that  we  have 
now  heavily  armed,  protected  steel  cruisers  steaming  over  all 
parts  of  the  world  with  less  change  of  deviation  of  the 
compass  than  the  wood-built  Erebus  and  Terror  of  Ross's 
Antarctic  expedition,  and  this  remarkable  result  could  not 
have  been  achieved  if  the  terrestrial  magnetic  observer  had 
not  done  his  work. 

Moreover,  if  magnetic  observations  are  not  continued 
the  secular  change  of  the  magnetic  elements  will  soon 
commence  to  mar  the  precision  with  which  our  rapidly 
moving  ships  traverse  the  globe. 

The  voyage  of  the  Challenger  in  1872-76  contributed 
the  most  valuable  series  of  observations  of  the  magnetic 
elements  in  modern  times,  when  the  large  areas  of  the 
principal  oceans  traversed  by  that  vessel  during  three  and 
a  half  years  are  taken  into  consideration.  These  observa- 
tions, combined  with  those  taken  from  every  available 
source,  both  British  and  foreign,  between  the  years  1865-87, 
formed  the  materials  from  which  the  magnetic  charts  of 
1880  were  compiled  (see  vol.  ii.,  Physics  and  Chemistry, 
part  vi.,  Voyage  of  H.MS.  "Challenger"). 

The  Challenger  only  crossed  the  Antarctic  circle  at  one 
point  in  longitude  78°  EM  and,  therefore,  although  we  know 
large  secular  changes  to  be  going  on  south  of  400  S.  we  have 
no  measure  of  the  amount,  nor  anything  like  an  accurate 
knowledge  of  distribution  of  the  earth's  magnetism  in  those 
regions.  This  points  to  the  necessity  for  a  new  Antarctic 
expedition. 

In  the  year  1888  the  late  Professor  J.  C.  Adams  was 
provided  with  a  complete  set  of  magnetic  charts  for  the  two 
epochs  1842-5  and  1880  previously  mentioned,  and  as  it 
was  known  he  had  directed  his  profound  mathematical 
ability  to  the  analysis  of  the  results  contained  in  them,  it 
was  hoped  that  some  new  and  important  light  might  be 


THE  BEARINGS  OF  MAGNETIC  OBSERVATIONS.     89 

thrown  upon  the  bare  facts  presented.      His  lamented  death 
occurred  without  his  publishing  any  results. 

If,  however,  reference  be  made  to  the  report  on  the 
magnetical  results  of  the  Challenger,  a  discussion  of  the 
secular  change  is  contributed  founded  in  a  great  measure 
on  a  comparison  of  those  charts.  The  outcome  of  this 
discussion  is  to  throw  considerable  doubt  upon  the  theory 
that  the  motion  of  the  magnetic  poles  round  the  terrestrial 
is  the  cause  of  secular  change  ;  in  fact,  that  the  magnetic 
poles  remain  fast,  and  we  must  look  elsewhere  for  the  cause 
whatever  it  may  be. 

Magnetic  observations  have  so  far  been  considered  in 
their  all-important  bearing  as  necessary  to  safe  navigation 
in  wood-built  ships,  and  in  a  far  higher  sense  as  indispens- 
able to  that  of  the  iron-  or  steel -built  ships  which  now 
cover  the  ocean  ;  the  magnetic  charts  hitherto  generally  re- 
quired for  these  purposes  being  those  on  which  normal 
lines  of  equal  values  have  been  given,  but  something  more 
is  now  needed. 

Observation  in  comparatively  recent  years  has  shown 
that  not  only  are  there  large  "  regional "  magnetic  dis- 
turbances extending  over  large  areas  of  land,  but  that  in 
moderate  depths  of  water  where  the  largest  ship  can  navi- 
gate freely,  the  land  below  is  also  found  to  have  considerable 
areas  of  local  magnetic  disturbance  which,  if  not  allowed  for, 
may  in  thick  or  foggy  weather  lead  ships  into  danger  by 
seriously  disturbing  their  compasses. 

The  United  States  have  done  excellent  work  in  pro- 
ducing charts  of  iso-magnetic  lines,  or  charts  in  which  the 
chief  local  magnetic  disturbances  are  recognised,  and  the 
full  results  of  observation  recorded.  The  maonetic  sur- 
veys  of  Riicker  and  Thorpe  in  the  British  Isles,  of  Moureau 
in  France,  of  Rijckevorsel  in  Holland  and  elsewhere,  have 
thrown  considerable  light  on  the  magnetic  conditions  of 
those  countries,  but  there  remain  whole  continents  to  be 
covered  by  the  observer. 

The  direction  of  the  iso-magnetics  too  from  the  deep 
sea  to  the  dry  land  of  the  coasts  is  an  extension  of  the 
subject,  which  the  observer  has  hardly  touched  as  yet,  but 


go  SCIENCE  PROGRESS. 

one  affecting  the  safety  of  navigation,  as  well  as  the  question 
that  has  been  raised,  whether  the  water  areas  of  the  globe 
are  as  a  whole  more,  or  less  magnetised  than  the  land  areas. 

To  possess  charts  of  iso-magnetic  lines  for  even  a  few 
countries  is  an  evidence  of  considerable  advance  in  the 
knowledge  of  terrestrial  magnetism,  for  if  reference  be 
made  to  Sabine's  lines  of  intensity  in  his  contribution  on 
the  magnetic  survey  of  North-West  America  it  will  be 
found  that  he  rejected  certain  observations  he  considered 
abnormal  and  defective,  which  Lefroy  the  observer  con- 
sidered to  be  his  best  and  naturally  retained  in  his  map  ; 
the  result  being  a  considerable  difference  in  the  form  of  the 
curves  adopted  by  the  two  magneticians,  Sabine  giving 
normal  curves,  Lefroy  iso-magnetics. 

Respecting  the  local  disturbances  of  the  needle  which 
have  been  so  clearly  proved,  the  question  naturally  arises, 
whence  the  cause  of  these  disturbances  ?  It  is  now  believed 
by  many,  if  not  finally  accepted,  that  Rlicker  and  Thorpe 
have  answered  the  question  by  the  results  of  their  laborious 
survey  of  the  British  Isles,  coupled  with  Riicker's  elegant 
investigations  as  to  the  permeability  of  specimens  of  the 
rocks  taken  from  the  localities  in  which  magnetic  dis- 
turbances were  found.  Their  answer  is  to  the  effect  that 
these  disturbances,  which  have  been  found  to  extend  over 
a  region  230  miles  long  by  about  110  miles  broad,  are 
due  to  induction  by  the  earth's  magnetism  in  rocks  of  dif- 
ferent permeability,  either  present  as  in  the  basalts  on  the 
surface  or  concealed  by  superficial  deposits. 

These  results  are  distinct  from  the  extraordinary  dis- 
turbances of  the  needle  when  in  the  immediate  vicinity  of 
permanently  magnetised  rocks,  and  when  the  radius  of  dis- 
turbance may  be  only  as  many  feet  as  the  extent  of  the 
regional  disturbance  is  in  miles. 

The  points  of  interest  in  the  question  of  regional 
magnetic  disturbance  are  not  confined  to  the  magnetician, 
for  the  geologist  cannot  afford  to  neglect  the  valuable  in- 
formation the  magnetic  needle  affords.  Thus  although 
Rlicker  and  Thorpe  have  since  made  a  second  and  more 
elaborate  survey  of  the  British   Isles,  their  remark  of  1890 


THE  BEARINGS  OF  MAGNETIC  OBSERVATIONS.     91 

that  "the  kingdom  can  be  divided  into  magnetic  districts 
in  which  the  relations  between  the  direction  of  the  disturb- 
ing forces  and  the  main  geological  characteristics  are  so 
suggestive  as  to  be  worthy  of  careful  statement  and  further 
investigation,"  not  only  holds  good,  but  has  received  con- 
firmation. 

The  mining  engineer  is  deeply  interested  in  a  know- 
ledge of  the  Declination.  Charts  of  normal  lines  are  of 
great  use  to  him  whether  above  or  below  the  earth's  surface, 
but  especially  below  when  he  has  no  other  guide.  To  such 
an  one  a  knowledge  of  regional  magnetic  disturbance  as  de- 
duced from  surface  observations  is  most  important,  as  it 
tells  him  that  he  is  in  the  neighbourhood  of  magnetic 
rocks,  the  disturbing  effect  of  which  on  his  compass  needle 
may  be  far  greater  in  the  depths  of  his  mine  and  turning  it 
into  a  treacherous  guide. 

We  have  now  considered  magnetic  observations  in  a 
measure  from  the  point  of  view  of  the  immediate  practical 
results  which  their  scientific  treatment  produces,  but  who 
will  say  in  this  great  maritime  nation  that  the  work  of  mag- 
netic observers,  even  if  solely  to  make  navigation  poss'ble, 
is  not  worthy  of  the  fullest  consideration  ? 

There  is  besides  a  vast  field  of  inquiry  for  the  observer  of 
terrestrial  magnetism  in  unravelling  thesecretsof  the  earth  con- 
sidered as  a  magnet,  and  the  ceaseless  change  of  its  magnetic 
condition  which  the  needle  tells  us  of,  for  which  no  immediate 
practical  result  can  be  foreseen,  yet  is  worthy  of  the  attention 
of  the  ablest  physicists  and  most  advanced  mathematicians. 

Inquiry  into  the  causes  of  the  secular  change  is  one 
requiring  the  fullest  attention,  but  observation  has  not  yet 
done  sufficient  work.  It  certainly  has  done  much  in  certain 
countries,  and  for  a  large  portion  of  the  world  as  regards 
secular  change  in  the  past,  and  data  obtained  for  predicting 
future  changes  for  a  few  years,  but  only  one  expedition  has 
examined  the  Antarctic  regions  magnetically,  and  it  is 
doubtful  if  any  substantial  progress  will  be  made  until  a 
second  expedition  is  made  thither,  one  profiting  by  the 
experience  of  its  precursor,  and  equipped  with  possibilities 
for  work  hardly  hoped  for  by  Ross. 


92  SCIENCE  PROGRESS. 

It  may  be  remarked  in  passing  that  a  remarkable 
alteration  in  the  amount  of  the  secular  change  has  been 
noticed  in  the  Declination  and  Inclination  at  the  following 
observatories  :  Bombay,  Batavia,  and  Hong  Kong  about 
the  period  of  the  eruption  of  Krakatoa  in  1883.  This  may 
be  only  a  coincidence,  but  may  it  not  also  point  to  the 
possibility  that  the  changes  below  the  surface  of  the  earth 
which  culminated  in  that  mighty  explosion,  and  may  still 
be  at  work,  have  had,  and  continue  to  have,  magnetic 
effects  which  are  recorded  by  the  needles  at  those  observa- 
tories ? 

Critical  investigations  have  for  many  years  been  directed 
to  the  elucidation  of  the  causes  of  the  observed  diurnal 
variations  of  terrestrial  magnetism.  This  work  was  long 
seriously  retarded  by  the  various  methods  adopted  at  different 
observatories  for  recording  their  results,  obliging  those  who 
entered  upon  a  comparison  of  such  results  to  go  through  a 
tedious  conversion  of  them  into  a  common  method.  It  may 
be  said  that  the  first  large  departure  from  this  objectionable 
practice  occurred  when  the  International  Polar  Inquiry  of 
1882-83  was  undertaken  by  the  various  expeditions. 

This  was  an  important  step  in  the  right  direction,  but 
there  remains  much  to  be  done,  as  shown  by  the  ten  re- 
ports of  the  British  Association  Committee  on  "the  best 
means  of  comparing  and  reducing  magnetic  observations  ". 
Their  last  report  consists  of  an  able  and  suggestive  paper 
by  Dr.  Chree,  being  the  analysis  of  the  results  of  five  years' 
observations  on  "quiet  days"  at  Kew,  and  is  well  worthy 
of  attention  as  indicative  of  the  present  state  of  our  know- 
ledge as  regards  the  diurnal  variation  of  the  three  magnetic 
elements. 

Such  investigations  only  encourage  one  in  the  hope  that 
the  much  required  observations  in  southern  latitudes  may 
be  undertaken.  The  observatories  at  the  Cape  and  Mel- 
bourne could  do  invaluable  work  if  it  were  carried  out  on 
the  lines  of  Kew,  for  example. 

Lastly,  what  more  is  there  to  be  said  about  magnetic 
observations  and  their  bearings  ?  We  do  not  know  why 
the  earth  is  a  magnet,  the  cause  of  the  secular  change  of  its 


THE  BEARINGS  OF  MAGNETIC  OBSERVATIONS.     93 

magnetism,  why  it  is  subject  to  solar  diurnal,  lunar  diurnal, 
sidereal  diurnal  and  the  other  variations  and  disturbances, 
nor  the  cause  of  magnetic  storms,  although  we  can  observe 
connections  between  them,  earth  currents,  and  aurorae. 
Whether  the  causes  of  all  these  exist  below  the  surface 
of,  or  are  external  to,  the  earth,  or  are  a  combination  of 
the  two,  has  still  to  be  learnt,  and  it  seems  hardly  too  much 
to  hope  that  the  restless  needle  will  sooner  or  later  be  the 
means  of  opening  up  sources  of  knowledge  invaluable  to 
cosmical  science,  as  well  as  to  those  only  concerned  with  the 
planet  upon  which  they  dwell. 

When  the  causes  of  the  secular  change  are  understood 
there  will  be  no  difficulty  in  providing  the  navigator  with 
magnetic  charts  for  years  in  advance,  much  as  the  tides  can 
now  be  tabulated  for  his  use.  In  the  latter  case  observa- 
tion has  done  its  work  for  several  frequented  ports,  in  the 
former  case  a  vast  amount  remains  to  be  done,  and  the 
word  that  goes  forth  is  still,  as  Lord  Kelvin  thrice  said 
on  a  kindred  subject  connected  with  ships'  magnetism, 
"  Observe". 

Ettrick   W.    Creak. 


THE  PRESENT  POSITION  OF  THE  CELL- 
THEORY. 

PART   I. 

A   FEW  years  ago  a  discussion  of  the  cell-theory  would 
have    seemed  superfluous.     To-day,  partly  because 
of  criticisms  which  have  been  directed  against  the  theory, 
partly  because  of  the  great  increase  of  our  knowledge  re- 
specting cell-structure,  the  advantage  and  even  the  necessity 
of  such  a  discussion  will  be  admitted  by  everybody  who  has 
read  and    reflected   on  the    subject.       In    what   follows,    I 
propose  to  examine  the   cell-theory  in  the  light  of  recent 
criticisms  and  researches.      I   set  out  with  the  intention  of 
avoiding  anything  in  the  shape  of  polemical  writing,  but  I 
fear  that  I  have  in  places  fallen  away  considerably  from  the 
course  which  I  had  proposed.      In  a  much  disputed  subject 
controversv  is  inevitable,  a  circumstance  which  need  not  be 
regretted,  for  controversy  is  the  whetstone  of  argument,  and 
obliges  those  who  engage  in  it  to  be  doubly  careful  both  of 
their  facts  and  of  the  language  in  which  they  express  them. 
My  antagonists  will,   I    hope,   give    me  the    credit    of  the 
desire  to  deal  fairly  with  their  arguments  and  criticisms,  and 
will  acquit  me  of  unnecessary  bitterness.      It  has  been  my 
object  to  elucidate  the  subject  in  hand  rather  than  to  try  to 
gain  a  dialectical  advantage. 

It  is  advisable,  before  entering  on  the  examination,  to 
have  a  clear  conception  of  what  the  cell-theory  really  is. 
This  is  the  more  necessary  because  one  of  its  most  recent 
critics,  Mr.  Adam  Sedgwick,  has  complained  than  nobody 
will  define  the  theory  in  an  exact  manner ;  it  is,  he  says,  a 
kind  of  phantom  which  takes  different  forms  in  different 
men's  eyes.  I  have  shown  in  another  place  that  this  state- 
ment is  hardly  fair,  because  there  are  some  authors  whose 
researches  on  cytology  entitle  them  to  speak  with  authority 
who  have  recently  defined  the  cell-theory  in  a  very  precise 
manner,  though  it  may  be  conceded  that  there  are  biologists 


THE  PRESENT  POSITION  OF  CELL-THEORY.      95 

whose  views  are  not  so  exact,  and  who  habitually  commit 
themselves  to  statements  which  on  careful  examination  may 
prove  to  be  altogether  untenable. 

It  was  pointed  out  some  time  since  by  Whitman,1  and  I 
have  since  emphasised  the  fact,2  that  in  his  broad  generalisa- 
tions Schwann  defined  the  cell-theory  in  a  very  exact  manner, 
and  that  the  words  originally  used  by  him  are  perfectly 
applicable  to  the  cell-theory  as  it  has  been  held  up  to  the 
present  time.  In  saying  this,  I  do  not  forget  that  Schwann 
held  some  very  erroneous  views  as  to  the  nature  and 
structure  of  cells,  which  he  regarded  as  vesicles,  filled  with 
fluid,  which  made  their  appearance  in  a  structureless  matrix, 
named  for  this  reason,  a  cytoblastema.  But  Schwann's 
work  consisted  of  two  parts,  a  statement  of  observations, 
which  have  proved  to  be  entirely  erroneous,  and  a  theory 
of  organisation,  which  has  been  very  fruitful  of  results.  He 
was  careful  to  say  that  his  theory  was  only  a  provisional 
explanation  which  suited  the  facts  as  nearly  as  possible,  and 
it  is  a  great  merit  of  the  theory  that  it  afforded  such  an  in- 
sight into  organisation  that  the  essential  part  of  it  did  not 
cease  to  be  serviceable  long  after  the  "facts"  on  which  it 
was  founded  were  shown  to  be,  for  the  most  part,  false. 
We  need  not  therefore  concern  ourselves  with  the  fact  that 
Schwann's  conceptions  of  the  origin  and  structure  of  cells 
were  false,  but  we  may  examine  his  theory  and  see  how 
much  of  it  we  may  hold  to,  and  how  much  we  must  reject 
at  the  present  day.3 

Schwann  was  a  very  cautious  writer,  and  the  quotations 
which  are  given  below  will  dispose  effectually  of  the  state- 

1  C.  O.  Whitman,  "On  the  Inadequacy  of  the  Cell-theory  of  Develop- 
ment, "Journal  of  Morphology,  viii.,  p.  639,  1893. 

2G.  C.  Bourne,  "A  Criticism  of  the  Cell-theory,"  Quart.  Jour.  Micro- 
scopical Science,  xxxviii.,  p.  137,  1895. 

3  A  large  part  of  Schwann's  theory  of  cells,  viz.,  that  part  of  it  which 
compared  cell-formation  to  the  process  of  crystallisation,  was  soon  shown 
to  be  untenable.  But  as  this  part  was  based  on  his  erroneous  views  on 
the  structure  and  origin  of  cells,  I  have  passed  it  over,  since  the  falsity  of 
his  views  on  this  subject  involved  the  falsity  of  as  much  of  his  theory  as 
was  founded  on  them. 


96  SCIENCE  PROGRESS. 

ment  which  stands  in  the  first  paragraph  of  Whitman's 
work,  that  he  believed  that  in  cell-formation  lies  the  whole 
secret  of  organic  development.  There  are,  says  Schwann, 
two  possible  theories  on  the  subject  of  organic  development: 
(i)  The  organism  theory,  namely,  that  there  is  an  inherent 
power  modelling  the  body  in  accordance  with  a  predominant 
idea.  (2)  The  physical  theory,  namely,  that  the  funda- 
mental powers  of  organised  bodies  agree  essentially  with 
those  of  inorganic  nature.  Rejecting  the  former  of  these 
two  theories  as  being  outside  the  domain  of  physical  science, 
Schwann  went  on  to  write  : x  "  We  set  out  with  the  sup- 
position that  an  organised  body  is  not  produced  by  a 
fundamental  power  which  is  guided  in  its  operation  by  a 
definite  idea,  but  is  developed  according  to  the  blind  laws 
of  necessity  by  powers  which,  like  those  of  inorganic 
nature,  are  established  by  the  very  existence  of  matter. 
As  the  elementary  materials  of  organic  nature  are  not  dif- 
ferent from  those  of  the  inorganic  kingdom,  the  source  of 
the  organic  phenomena  can  only  reside  in  another  com- 
bination of  these  materials,  whether  it  be  in  a  peculiar 
mode  of  union  of  the  elementary  atoms  to  form  atoms  of 
the  second  order,  or  in  the  arrangement  of  these  con- 
glomerate molecules  when  forming  either  the  separate 
morphological  elementary  parts  of  organisms,  or  the  entire 
organism.  We  have  here  to  do  with  the  latter  question 
solely,  whether  the  cause  of  organic  phenomena  lies  in  the 
whole  organism  or  in  its  separate  elementary  parts.  If 
this  question  can  be  answered  a  further  inquiry  still  re- 
mains as  to  whether  the  organism  or  its  separate  elementary 
parts  possess  this  power  through  the  peculiar  mode  of 
combination  of  the  conglomerate  molecules  or  through  the 
mode  in  which  the  elementary  atoms  are  united  into  con- 
glomerate molecules." 

Is  it  not  perfectly  clear  from  this  that  Schwann  fully 
recognised  that  there   was   a  further   question   underlying 

xTh.  Schwann,  Microscopical  Researches  into  the  Accordance  in  the 
Structure  and  Growth  of  Animals  and  Plants.  Translated  by  Henry 
Smith.     London:  Printed  for  the  Sydenham  Society,  1847. 


THE  PRESENT  POSITION  OF  CELL-THEORY.       97 

the  cell-theory,  and  do  not  the  words  which  he  used  with 
regard  to  the  union  of  elementary  atoms  to  form  atoms  of 
the  second  order  show  a  prescience  of  the  assumptions 
which  would  have  to  be  made  to  explain  the  powers  mani- 
fested by  cells  ?  Because  he  confined  himself  to  the  one 
question,  it  is  not  fair  to  say  that  Schwann  had  not  a  clear 
appreciation  of  the  importance  of  the  other.  I  may  relate, 
in  this  connection,  an  anecdote  which  will  finally  clear 
Schwann's  reputation  from  the  reproach  fastened  upon  it. 
Professor  Lankester  tells  me  that  about  the  time  when  a 
sort  of  jubilee  was  held  in  Schwann's  honour  at  Liege  in 
1878,  he  was  introduced  to  him,  and  ventured  to  ask  in 
the  course  of  conversation  how  it  was  that  after  the  publica- 
tion of  his  famous  essay  he  had  so  long  been  silent. 
Schwann  answered  that  he  had  not  been  idle,  but  that 
ever  since  he  had  been  unsuccessfully  occupied  in  trying  to 
find  out  the  secret  of  the  constitution  of  the  cell. 

To  return  to  the  question  propounded  by  Schwann, 
does  the  cause  of  organic  phenomena  lie  in  the  organism  or 
in  its  separate  elementary  parts,  the  cells  ?  He  answers 
very  decidedly,  in  the  separate  elementary  parts,  and  gives 
the  following  reasons  for  his  answer:  "  All  organised 
bodies  are  composed  of  essentially  similar  parts,  namely,  of 
cells  ;  these  cells  are  formed  and  grow  in  accordance  with 
essentially  similar  laws,  and  therefore  these  processes  must 
in  every  instance  be  produced  by  the  same  powers.  Now 
if  we  find  that  some  of  these  elementary  parts  not  differing 
from  the  others  are  capable  of  separating  themselves  from 
the  organism  and  pursuing  an  independent  growth,  we  may 
thence  conclude  that  each  of  the  other  elementary  parts — 
each  cell — is  already  possessed  of  the  power  to  take  up  fresh 
molecules  and  grow,  and  that  therefore  each  elementary 
part  possesses  a  power  of  its  own,  an  independent  life,  by 
means  of  which  it  would  be  enabled  to  develop  itself  in- 
dependently if  the  relations  which  it  bore  to  external  parts 
were  but  similar  to  those  in  which  it  stands  in  the  organism. 
The  ova  of  animals  afford  us  examples  of  such  independent 
cells  apart  from  the  organism." 

A  little  further  on  he  says  :  "  In  inferior  plants  any  given 

7 


98  SCIENCE  PROGRESS. 

cell  may  be  separated  from  the  plant  and  can  grow  alone. 
So  that  here  are  whole  plants  consisting  of  cells  which  can 
be  positively  proved  to  have  independent  vitality.  Now  as 
all  cells  grow  according  to  the  same  laws,  and  consequently 
the  cause  of  growth  cannot  in  one  case  lie  in  the  cell,  and 
in  another  in  the  whole  organism,  and  since  it  may  be 
further  proved  that  some  cells,  which  do  not  differ  from  the 
rest  in  their  mode  of  growth,  are  developed  independently, 
we  must  ascribe  to  all  cells  an  independent  vitality,  that  is 
such  combinations  of  molecules  as  occur  in  any  single  cell 
are  capable  of  setting  free  the  power  by  which  it  is  enabled 
to  take  up  fresh  molecules.  The  cause  of  nutrition  and 
growth  resides  not  in  the  organism  itself  but  in  its  separate 
elementary  parts.  .  .  .  The  manifestation  of  the  power 
which  resides  in  the  cell  depends  upon  conditions  to  which 
it  is  subject  only  when  in  connection  with  the  whole  or- 
ganism." 

The  whole  theory  is  very  succinctly  summed  up  in  the 
following  passage  :  "  The  elementary  parts  of  all  tissues  are 
formed  of  cells  in  an  analogous  though  very  diversified 
manner,  so  that  it  may  be  asserted  that  there  is  one  uni- 
versal principle  of  development  for  the  elementary  parts  of 
organisms,  however  different,  and  that  this  principle  is  the 
formation  of  cells  ". 

No  doubt  objection  may  be  taken  to-day  to  the  uni- 
versality of  this  statement,  but  if  we  modify  the  last  part 
of  it  and  read  "  that  the  most  general  principle  of  develop- 
ment for  organisms,  however  different,  is  the  formation  of 
cells,"  we  shall  have  very  nearly  expressed  the  truth,  as  we 
know  it  at  the  present  day. 

I  have  found  it  necessary  to  quote  Schwann's  work  at 
considerable  length,  and  to  repeat  more  emphatically  what 
I  stated  in  my  previous  essay  on  Epigenesis  and  Evolution.1 
Dr.    Whitman,2    in    a    reply    which    deals    partly  with   my 

1  G.  C.  Bourne,  "Epigenesis  and  Evolution,"  "  Science  Progress," 
vol.  i.,  1894. 

2  C  O.  Whitman,  Evolution  and  Epigenesis.  Boston  :  Ginn  &  Co., 
1895. 


THE  PRESENT  POSITION  OF  CELL-THEORY.      99 

criticisms,  and  partly  with  the  much  more  weighty  argu- 
ments brought  forward  at  the  same  time  by  Dr.  Oscar 
Hertwig,  says  that  my  criticisms,  in  so  far  as  they  are 
directed  against  the  inadequacy  of  the  cell-theory  of  develop- 
ment, are  largely  the  result  of  misunderstanding  ;  this  may 
in  part  be  true,  but  I  cannot  have  misunderstood  the  simple 
meaning  of  his  first  paragraph,  and  I  wish  to  insist  on  the 
fact  that  the  cell-theory,  as  it  was  promulgated  by  Schwann, 
did  not  regard  cell-formation  as  the  whole  secret  of  organic 
development,  and  that  the  cell  was  not,  in  the  mind  of  the 
author  of  the  cell-theory,  the  alpha  and  omega  of  both 
morphological  and  physiological  research  in  the  animal 
kingdom.  If  this  is  clearly  understood  at  the  outset,  it  will 
help  to  remove  much  possible  misunderstanding. 

But,  as  Mr.  Sedgwick  has  rightly  said,  we  have  to  deal 
not  only  with  what  its  authors  thought,  but  with  the  cell- 
theory  as  it  is  understood  and  taught  at  the  present  day. 
I  have  already  pointed  out *  that  the  most  recent  definition 
of  the  cell-theory  is,  to  all  intents  and  purposes,  identical 
with  the  broader  generalisations  of  Schwann.  Dr.  Oscar 
Hertwig  writes  : 2  "  Animals  and  plants,  so  dissimilar  in  their 
outward  appearances,  are  similar  in  the  essentials  of  their 
anatomical  structure,  since  both  are  composed  of  similar 
elementary  parts  which  for  the  most  part  are  only  recognis- 
able by  the  microscope.  .  .  .  Since  the  cells,  into  which 
the  anatomist  resolves  vegetable  and  animal  organisms,  are 
the  bearers  of  the  vital  processes,  they  are,  as  Virchow  has 
expressed  himself,  the  vital  units.  Viewed  from  this  stand- 
point the  whole  life  process  of  a  composite  organism  appears 
to  be  nothing  else  than  the  extremely  complicated  result  of 
the  individual  life  processes  of  its  numerous  and  variously 
functional  cells."  This  is  simply  a  restatement  in  other 
words  of  two  of  the  fundamental  principles  of  Schwann, 
namely  (1)  that  the  elementary  parts  of  all  tissues  are  formed 

1  G.  C.  Bourne,  "A  Criticism  of  the  Cell-theory,"  Quart.  Jour.  Micr. 
Science,  vol.  xxxviii.,  p.  137,  1895. 

2  O.  Hertwig,  Die  Zelle  utid  die    Gewebe.      Berlin :    R.    Friedlander 
und  Sohn,  1893. 


ioo  SCIENCE  PROGRESS. 

of  cells  ;  (2)  that  the  cause  of  nutrition  and  growth  resides 
not  in  the  organism  but  in  its  separate  elementary  parts. 

The  attacks  which  have  recently  been  directed  against 
the  cell-theory  may  be  resolved  into  contradictions  of  these 
two  fundamental  propositions.  On  the  one  hand  there  is 
the  considerable  number  of  cytologists,  whose  opinions 
may  be  taken  to  be  summed  up  in  Whitman's  essay  on 
the  inadequacy  of  the  cellular  theory,  who  deny  the  second 
proposition,  and  in  so  doing  implicitly  deny  the  truth  of 
the  first.  They  would  say  that  the  cause  of  nutrition  and 
growth  does  not  reside  in  the  cells  considered  as  elementary 
parts,  but  in  parts  still  more  elementary,  the  ultimate  vital 
units  of  which  the  cells  themselves  are  composed.  On 
the  other  hand  Mr.  Adam  Sedgwick  denies  the  first  pro- 
position in  toto.  He  states  boldly  that  the  elementary 
parts  of  tissues  are  not  formed  of  cells,  but  of  a  continuous 
mass  of  vacuolated  protoplasm  containing  nuclei.1  These 
objections,  though  they  are  raised  from  different  stand- 
points, are  not  irreconcilable,  but  it  will  be  convenient  to 
deal  with  them  separately.  First  let  us  consider  the 
objections  to  the  cell  as  an  ultimate  vital   unit. 

These  objections  are  of  long  standing.  They  were  first 
brought  forward  by  Briicke  2  in  1861  ;3  not  long  afterwards 

1  Since  this  was  written  Mr.  Sedgwick  has  published  a  further  account 
of  his  views,  which  makes  it  necessary  to  modify  this  statement.  See 
infra. 

2  Ernst  Briicke,  "  Die  Elementarorganismen,"  Sitzungsberichte  der  K. 
Akademie  der  Wissenschaften,  Wien,  bd.,  xliii.,  p.  381,  1861. 

3  Delage  points  out  that  the  merit  of  regarding  protoplasm  as  an 
organised  substance  belongs  to  Dujardin,  and  not  to  Brucke.  At  the 
same  time  he  points  out  the  essential  difference  between  Briicke's  concept 
of  organisation  and  that  of  Dujardin,  greatly  to  the  advantage  of  the  latter  : 
"  La  difference  entre  Dujardin  et  Brucke  est  tres  simple.  Le  premier  a 
devine  l'existence  de  structures  que  le  microscope  demontre  aujourd'hui ; 
tandis  qu'en  introduisant  dans  la  conception  de  protoplasma  cette  notion 
acceptee  avec  enthousiasme,  d'organismes  tres  compliques  et  invisibles, 
Brucke  a  ouvert  la  porte  aux  nombreuses  theories  speculatives  qui  cher- 
chent  a  imaginer  la  structure  de  ces  organismes  pour  expliquer  par  elles  les 
phenomenes  de  la  vie."  Delage  adopts  the  expression  organisation,  saying  : 
"  Le  protoplasme  n'est  pas  simplement,  comme  on  l'a  cru  longtemps,  une 
substance  chimique  organique,  mais  il  est  organise,  c'est-a-dire  possede  une 


THE  PRESENT  POSITION  OF  CELL-THEORY.     101 

Herbert  Spencer  followed  with  his  theory  of  physiological 
units.  Darwin's  theory  of  pangenesis  expressed  the  same 
idea,  and  more  recently  Nageli,  De  Vries,  Wiesner,  Weis- 
mann  and  others  have  entered  the  same  or  at  least  similar 
objections  to  the  cell-theory.  Even  Oscar  Hertwig,  although 
he  appears  in  the  sentence  above  quoted  to  give  his 
adherence  to  the  view  that  the  cell  is  a  vital  unit,  abandons 
this  concept,  for  all  practical  purposes,  in  the  latter  part  of 
his  book  ;  for  he  says,  in  a  most  unmistakable  manner, 
that  the  cell  is  an  organism  composed  of  ultimate  units 
which  he  calls  idiosomes. 

Each  author  whose  name  I  have  quoted  has  a  somewhat 
different  account  to  give  of  the  ultimate  constitution  of  the 
cell.  But  the  points  on  which  they  disagree  are  of  subor- 
dinate importance  ;  they  are  all  agreed  on  the  main  issue, 
that  the  vital  activities  manifested  by  the  cell  are  not  to  be 
explained  by  the  visible  constitution  and  structure  of  the 
cell  itself,  nor  by  the  mere  chemical  elements  of  which  the 
protoplasm  of  the  cell  is  composed.  Each  of  them  avers 
that  the  cell  is  organised,  which  means  that  it  is  made  up  of 
countless  organic  units  of  a  lower  order,  differing  among 
themselves,  and  arranged  in  groups  and  sub-groups  within 
the  cell  in  a  manner  analogous  to  that  in  which  the  cells 
themselves  are  arranged  in  a  composite  organism.  Since 
there  is  so  general  an  agreement  in  fundamental  principle, 
1  am  spared  the  necessity  of  examining  each  separate  theory 
of  ultimate  vital  units  in  detail ;  should  anybody  wish  for  a 
condensed  account  of  the  various  theories  he  will  find  it  in 
Weismann's  introduction  to  his  work  on  the  Germ  Plasm.1 

structure  d'un  ordre  plus  eleve  que  la  structure  atomique  des  molecules 
chimiques  des  composes  organiques  non  vivants  ".  No  fault  can  be  found 
with  this  definition,  but  would  it  not  be  better  to  adopt  some  other  term  to 
express  this  extra  complexity  of  structure  rather  than  "  organisation,"  which  is 
inseparably  connected  with  our  ideas  of  the  composition  of  the  bodies  of 
higher  animals  and  plants?  For  Brucke  the  organisation  of  protoplasm 
was  the  same  in  kind  as  the  organisation  of  higher  animals  :  for  Dujardin 
it  was  something  different,  and  had  best  be  expressed  by  a  different  term. 
Delage  puts  the  word  structure  in  italics. 

1  Still  better  in  Delage's  book,  referred  to  further  on. 


102  SCIENCE  PROGRESS. 

The  point  for  present  consideration  is  this  :  Is  it  neces- 
sary for  the  explanation  of  vital  phenomena  to  assume 
the  existence  of  ultimate  vital  particles,  so  minute  as 
to  be  invisible  with  the  best  microscopical  powers 
which  we  possess,  each  of  which  is  to  be  considered 
as  being  in  posse  an  independent  organism  capable  of 
displaying  some  of  the  most  characteristic  of  vital  pheno- 
mena, viz.,  assimilation,  growth,  metabolism,  reproduction 
by  division  ? 

As  it  will  be  necessary  to  refer  frequently  to  these 
assumed  vital  units,  I  must  call  them  by  some  name,  and  I 
shall  use  Weismann's  term  biophor,  without  meaning  to 
exclude  the  conceptions  of  other  authors,  the  pangenes  of 
De  Vries,  the  plasomes  of  Wiesner  and  so  forth.  I  use  the 
term  biophor  in  the  sense  of  Lebenstrager,  the  bearer  of  the 
vital  properties,  without  necessarily  implying  that  it  pos- 
sesses all  the  particular  properties  assigned  by  Weismann 
to  his  biophors. 

Whatever  the  point  from  which  the  different  authors 
have  started,  they  all  postulate  the  existence  of  minute 
biophors  on  the  grounds  that  the  vital  phenomena  exhibited 
by  cells,  say  by  an  Amoeba,  or  by  the  ovum  of  a  Metazoon, 
imply  the  existence  of  an  organisation  adequate  to  the 
production  of  the  observed  processes.  The  life  processes 
are  too  various  and  too  complicated  in  their  kind  to  be 
explained  by  the  visible  constitution  of  protoplasm,  even  if 
it  be  allowed,  as  it  generally  is  allowed,  that  protoplasm  is 
not  a  chemical  compound  of  fixed  molecular  composition 
but  a  mixture  of  many  chemical  substances,  each  having  a 
molecular  composition  of  some  considerable  complexity.  I 
have  already  shown  that  Schwann  himself  was  possessed  of 
such  an  idea,  which  he  expressed  sufficiently  clearly  when 
he  referred  to  "  a  peculiar  mode  of  union  of  the  atoms 
to  form  atoms  of  the  second  order,"  but  he  did  not  attempt 
to  follow  out  the  idea,  confining  himself  to  the  inquiry 
into  "  the  arrangement  of  these  conglomerate  molecules 
when  forming  either  the  separate  elementary  parts  of 
organisms  or  the  entire  organism  ".  The  term  consdomer- 
ate  molecule  is  in  fact  synonymous  with  the  term  biophor 


THE  PRESENT  POSITION  OF  CELL-THEORY.     103 

in  the  sense  in  which  I  am  using  it,  for  the  biophor  or 
ultimate  vital  unit  is  held  to  be  an  aggregate  of  chemical 
molecules  ;  the  constitution  attributed  to  it  is  that  it  is  made 
up  of  many  different  kinds  of  molecules,  just  as  a  molecule 
may  be  composed  of  several  different  kinds  of  atoms.  I  shall 
have  to  refer  aram  to  the  difficulties  which  still  remain  if 
we  accept  the  hypothesis  that  a  group  of  different  molecules 
is  able  to  exhibit  the  vital  functions  which  are  necessarily 
attributed  to  a  biophor.  Before  proceeding  to  criticism  I 
must  try  to  give  as  fairly  as  I  can  the  grounds  for  believing 
in  the  existence  of  biophors.  To  put  the  matter  as  briefly 
as  possible,  the  theories  of  ultimate  vital  units  are  the  resuh 
of  attempts  to  make  a  mental  analysis  of  living  substance 
Chemical  analysis  is  impossible,  for  in  the  process  the 
living  substance  is  destroyed  as  such  and  becomes  dead 
substance,  possessed  of  different  and  much  less  important 
properties.  One  fact  of  great  importance,  however,  is 
learnt  from  chemical  analysis,  and  it  was  appreciated  by 
Schwann,  namely,  that,  to  use  his  original  words,  "the 
elementary  materials  of  organic  nature  are  not  different 
from  those  of  the  inorganic  kingdom  "  ;  hence  it  has  been 
inferred,  with  all  reason,  that  the  powers  of  organic  nature 
are  essentially  the  same  as  those  of  inorganic  nature,  and 
are  established  by  the  very  existence  of  matter.  It  is  only 
necessary  to  mention  this  because  there  has  recently  been 
a  tendency  in  some  quarters  to  call  in  the  assistance  of  some 
mysterious  "  vital  force  "  ;  a  tendency  begotten  no  doubt  by 
the  apparent  futility  of  all  attempts  to  find  an  explanation 
on  mechanical  and  chemical  principles  of  the  fundamental 
powers  of  organic  nature,  assimilation  and  metabolism. 
This,  however,  need  not  detain  us  ;  we  have  to  consider 
the  process  of  reasoning  which,  in  default  of  assistance 
from  chemical  analysis,  has  led  so  many  distinguished 
observers  and  thinkers  to  analyse  the  cell  into  other  com- 
ponents, and  those  again  into  others  of  a  lower  grade, 
until  the  biophor,  the  smallest  particle  of  possible  life,  is 
reached. 

The  weightiest  reason  which   I   have  been  able  to  dis- 


104  SCIENCE  PROGRESS. 

cover  is  given  by  von  Sachs.1  According  to  this  author, 
whose  views  are  in  agreement  with  those  of  Nageli  on  this 
subject,  it  is  necessary  for  the  explanation  of  certain  pheno- 
mena exhibited  by  organic  substances  that  we  should  assume 
the  existence  of  combinations  of  molecules  which  form  very 
large  numbers  of  small  particles  or  micellae  as  Nageli  calls 
them.  One  of  the  most  important  of  these  phenomena  is 
the  imbibition  of  water.  Dry  organic  substances,  such  as 
gelatine,  when  placed  in  water,  imbibe  it  and  increase  in 
volume  to  a  very  considerable  extent.  The  increase  in 
volume  produced  by  the  swelling  up  in  water  is  almost 
equal  to  the  volume  of  water  which  has  been  absorbed. 
The  imbibition  of  water  in  such  a  case  is  something  very 
different  from  the  imbibition  of  water  by  a  porous  inorganic 
body,  such  as  gypsum,  unglazed  porcelain,  etc.  The  latter 
substances  are  full  of  small  visible  and  invisible  cavities  or 
pores,  which  in  the  dry  state  contain  air.  The  water  passes 
into  these  cavities  or  pores  according-  to  the  laws  of  capil- 
larity, and  in  so  doing  displaces  the  air,  which  is  forcibly 
expelled  and  can  be  collected  and  measured  ;  there  is  no 
pushing  asunder  of  solid  parts,  as  is  shown  by  the  fact  that 
the  porous  body  is  not  perceptibly  enlarged  by  the  water 
which  has  penetrated  into  it.  But  the  water  penetrating 
into  gelatine  expels  no  air,  it  does  not  enter  by  capillarity 
into  spaces  previously  existent,  but  forces  its  way  between 
the  particles  of  the  dry  substance,  pushing  these  asunder, 
and  so  causing  the  considerable  increase  in  volume.  The 
particles  thus  pushed  asunder  are  the  micellae,  and  although 
they  are  pushed  further  apart  from  one  another,  they  do 
not  completely  lose  their  connection.  Each  micella  may  be 
regarded  as  being  surrounded  by  an  envelope  of  water 
when  in  the  moist  state  ;  in  the  dry  state  the  micellae  com- 
posing the  substance  are  in  mutual  contact.  This  familiar 
phenomenon  of  the  swelling  of  organic  substances  by  the 
imbibition  of  water  is  contrasted  by  von  Sachs  with  the 
process  of  solution  of  a  salt.      In  the  latter  case  the  water 

XJ.   von   Sachs,  Lectures  on  the  Physiology  of  Plants,   translated   by 
H.  Marshall  Ward.     Oxford,  Clarendon  Press,  pp.  205  and  sq.,  1887. 


THE  PRESENT  POSITION  OF  CELL-THEORY.     105 

seizes  on  the  molecules  of  a  crystal  and  takes  them  in 
between  its  own  molecules  ;  in  the  former  case  the  dry 
organic  body  seizes  on  the  molecules  of  water  and  forces 
them  between  its  own.  These  reasons  are  held  by  von 
Sachs  and  Nageli  to  be  among  the  weightiest  for  regarding 
protoplasm  as  an  "organised"  body,  in  the  sense  of  being 
made  up  of  micellae,  and  not  as  being  a  structureless  slime 
or  fluid. 

No  doubt  they  are  weighty  reasons  for  regarding  or- 
ganic substances  such  as  gelatine,  starch  grains,  cell  walls, 
etc.,  as  being  composed  of  combinations  of  polyatomic 
molecules  into  groups  of  a  higher  order,  and  there  is  no 
objection  to  giving  these  groups  a  name,  such  as  micellae. 
But  the  admission  that  such  groups  exist  does  not  really 
bring  us  much  nearer  to  an  explanation  of  the  phenomena 
of  life.  Von  Sachs  himself  points  out  that  even  in  the 
region  of  pure  chemistry  it  is  necessary  to  assume  that 
polyatomic  molecules  are  grouped  into  closer  molecular 
unions,  thus  giving  rise  to  chemical  properties  which  did 
not  belong  to  the  individual  molecules. 

Gelatine,  starch  grains  and  cellulose  are  not  living  but 
dead  substances,  and  the  fact  that  the  behaviour  of  dead 
organic  substance  finds  an  explanation  on  a  theory  of 
micellar  structure  is  but  a  very  small  step  towards  the 
explanation  of  the  very  different  behaviour  of  living  sub- 
stance. The  micellae  may  exist  in  the  organic  substances 
in  question,  but  they  are  not  to  be  confounded  with  biophors ; 
the  very  fact  that  the  properties  of  dead  substances  may  be 
attributed  to  their  existence  shows  that  they  cannot  be  con- 
sidered as  bearers  of  vital  properties. 

In  point  of  fact  the  living  substance,  which  we  generalise 
under  the  name  of  protoplasm,  behaves  quite  differently 
in  respect  of  the  imbibition  of  water  to  the  dead  substances 
which  are  derived  from  it.  An  amoeba  or  an  infusorian, 
living  in  the  water,  does  not  imbibe  it  as  a  mass  of  gelatine 
would.  But  when  it  dies  in  the  same  water  it  immediately 
begins  to  swell  up,  and  eventually  bursts  and  disintegrates. 
So  that  we  see  that  with  respect  to  this  very  property  which 
is  held  to  be  a  reason  for  assuming  a   micellar  structure  of 


io6  SCIENCE  PROGRESS. 

protoplasm,  the  actual  living  substance  does  not  exhibit  the 
property,  whilst  the  same  substance  when  dead  does. 
Clearly  then,  the  admission  that  protoplasm  has  a  micellar 
structure,  that  is,  that  it  is  composed  of  minute  and  invisible 
particles  consisting  of  groups  of  polyatomic  molecules,  does 
not  involve  the  admission  that  there  are  ultimate  vital  units, 
biophors,  which  reside  in  the  cell-like  organisms  within  the 
cell-organism.  This  distinction  indeed  has  already  been 
made  and  dwelt  upon  at  some  length  by  Weismann  (op. 
cit.,  pp.  41  and  42). 

It  follows  then  that  whilst  we  may  freely  admit  that 
protoplasm,  and  also  various  inert  organic  substances,  are 
composed  of  micellae,  and  are  therefore  "organised"  in  the 
sense  spoken  of  by  von  Sachs,  we  have  still  to  consider  the 
evidence  for  the  existence  of  biophors.  At  the  outset  of 
this  inquiry  we  meet  with  a  difficulty  in  that  the  existence 
of  biophors  is  assumed  by  most  authors  as  a  means  of  ex- 
plaining the  phenomena  of  heredity,  and  this  opens  up  a 
wide  range  of  questions  into  which  it  is  not  the  purpose  of 
this  essay  to  enter.  But  it  has  well  been  pointed  out  by 
Wiesner  that  if  minute  vital  elements  occur  at  all,  those 
same  units  which  make  life  possible,  and  control  assimila- 
tion and  growth,  must  also  be  the  agents  in  bringing  about 
the  phenomena  of  heredity.  This  view,  which  commends 
itself  to  everybody,  implies  that  the  biophors  have  only 
secondarily  acquired  historic  qualities,  and  that  they  are 
primarily  concerned  in  the  production  of  the  fundamental 
processes  of  life.  We  may  therefore  dismiss  for  the  present 
purpose  the  complications  introduced  by  heredity  and  con- 
fine our  inquiry  to  the  functions  of  biophors  as  bearers  of 
the  essential  vital  qualities. 

It  is  urged  in  favour  of  a  theory  of  biophors  that  life 
must  be  connected  with  a  material  unit  of  some  sort  (Weis- 
mann) ;  that  function  presupposes  structure  (Whitman),  and 
that  the  structure  necessary  for  the  exhibition  of  such 
complicated  functions  as  those  of  living  protoplasm  cannot 
be  of  such  a  simple  molecular  kind  even  as  the  micellar 
structure  postulated  by  von  Sachs  and  Niigeli,  but  must 
consist  of  a  definite  arrangement,  an  architecture  or  organ- 


THE  PRESENT  POSITION  OF  CELL-THEORY.     107 

isation  of  separate  living  particles,  the  aggregate  functions 
of  which  produce  the  vital  phenomena.  It  is  further  urged 
in  favour  of  this  view  of  organisation,  that  in  almost  all 
cells  we  are  able  to  recognise  structures  under  the  micro- 
scope  each  of  which  behaves  in  respect  of  growth  and 
multiplication  in  a  manner  analogous  to  that  in  which  the 
cell  behaves.  Not  only  the  nucleus  but  also  the  chromatin 
bodies,  the  microsomata  of  which  these  are  composed,  the 
centrosomes,  the  green  chromatophores  of  plant  cells,  may- 
be observed  to  increase  in  size,  i.e.,  to  grow  and  to  multiply 
by  division,  and  it  is  held  that  this  is  proof  that  the  ultimate 
particles  composing  these  bodies  must  assimilate,  grow  and 
divide  in  a  manner  similar  to  that  in  which  cells  assimilate, 
otow  and  divide. 

This  view,  whilst  receiving  a  considerable  measure  of 
support  from  other  sources,  has  been  most  energetically 
supported  by  Wiesner,1  whose  extensive  work  on  the  subject 
has  received  the  weighty  approval  of  Weismann.  Wiesner 
refers  in  detail  to  the  various  structures  in  the  form  of 
granules  or  corpuscles  which  may  be  observed  in  animal 
and  vegetable  protoplasm,  and  he  attributes  to  one  and  all  of 
them  the  powersof  assimilation  and  multiplication  bydivision. 
Nor  does  he  confine  himself  to  the  living  substance  gener- 
ally recognised  under  the  name  of  protoplasm.  He  labours 
at  great  length  to  prove  that  the  cell  wall,  so  often  con- 
sidered as  an  inert  non-living  product  of  living  protoplasm, 
is  not  in  fact  dead,  but  contains  a  living  substance  distin- 
guishable under  the  name  dermatoplasm,  and  ultimately 
composed  of  structural  elements  of  the  same  fundamental 
nature  as  that  of  the  cytoplasm.  These  ultimate  particles 
are  the  fi/asomes,  which  form  the  central  point  of  his  theory 
of  the  constitution  of  living  matter.  Further  than  this  he 
accepts  in  full  the  theory  of  De  Vries  with  regard  to  vacuoles, 
and  considers  them  to  be  just  as  much  independent  organ- 
isms as  the  chromosomes,  the  centrosomes,  the  chlorophyll 
bodies  and  other  things.     This  theory  of  vacuoles,  which 

1  J.  Wiesner,  Die  Elementar  structur  und das  Wachsthum  der Lebendem 
Substanz.     Wien  :  Alfred  Holder,  1892. 


108  SCIENCE  PROGRESS. 

assumes  that  they  are  products  of  minute  bodies  called 
tonoplasts,  is  of  itself  improbable,  and  is  contrary  to  the 
teaching  of  observations  which  may  readily  be  made  on  the 
constitution  and  behaviour  of  vacuoles  in  living  protoplasm. 
It  has  been  shown  by  Butschli l  that  the  contractile  and 
other  vacuoles  of  Protozoa  continually  make  their  appear- 
ance without  owing  their  origin  to  the  division  of  previously 
existing  vacuoles.  It  is  not  possible  to  go  into  details  here, 
but  the  reader  will  find  a  full  discussion  of  this  question  in 
Butschli's  work  (p.  230)  as  also  a  resume  of  the  various 
theories  which  have  from  time  to  time  been  put  forward  on 
the  subject  of  the  granular  theory  of  protoplasm.  But  even 
if  peculiar  views  on  the  nature  of  vacuoles  be  laid  aside, 
the  gist  of  Wiesner's  arguments  is  not  materially  weakened. 
None  of  the  structures  which  are  observable  in  protoplasm 
are  observed  to  originate  neogenetically  :  they  are  all,  he 
says,  derived  directly  by  division  from  pre-existing  struc- 
tures of  similar  character.  In  short,  he  fully  accepts  the 
aphorism  put  forward  somewhat  earlier  by  Altmann  : 
"  Omne  granulum  e  granulo  ".  Wiesner  does  not  definitely 
say  that  the  various  particles  observable  in  protoplasm  are 
to  be  severally  identified  with  the  ultimate  vital  units,  his 
plasomes.  Some  of  them  may  be  individual  plasomes,  but 
the  majority  of  them  are,  he  thinks,  aggregates  of  plasomes, 
units  of  a  hioher  order  which  in  turn  are  combined  to  form 
the  still  higher  unit  the  cell.  Thus  he  presents  a  scheme 
of  organisation  which,  instead  of  taking  the  cell  as  the 
lowest  structural  unit,  goes  several  grades  lower  ;  instead 
of  the  old  conception  of 

organ — tissue — cell, 

he  represents  the  scheme  of  organisation  as  being 

organ — tissue — cell — granules — plasomes. 

A  detailed  criticism  of  Wiesner's  views  would  occupy  a 

much  larger  space  than  I  have  at  my  disposal,   and  such  a 

criticism    is   unnecessary,  since   all   that   need   be   said   has 

1  O.  Butschli,  Investigations  on  Microscopic  Foams  and  Protoplasm. 
Authorised  translation  by  E.  A.  Minchin.  London  :  A.  and  C.  Black, 
1894. 


THE  PRESENT  POSITION  OF  CELL-THEORY.     109 

already  been  set  forth  by  other  authors  in  their  criticisms  of 
similar  theories,  particularly  by  Biitschli  {loc.  cit.,  p.  195) 
and  O.  Hertwig,  both  of  whom  occupy  themselves  with 
Altmann's  views,  which  are  to  all  intents  and  purposes 
identical.  Only  a  few  of  the  most  important  points  need  be 
touched  upon  here. 

It    is   certainly   a    remarkable    fact,    and    confirmed   by 
abundant  experience,  that  many  of  the  constituent  parts  of 
cells  are  produced  by  divisions  which  recall  the  divisions  of 
the  cell  itself.     The  nucleus  is  the  most  important  and  the 
most  familiar  constituent  of  the  cell  :  it  is  within  the  experi- 
ence of  every  biologist  that   nuclei   are  never  observed  to 
originate  neogenetically,  but   always   by   division  of  a  pre- 
existing nucleus.    The  chromatin  elements  of  the  nucleus  may 
be  shown  to  be  composed  of  minute  particles,  the  so-called 
chromosomes,  and  these  reproduce  themselves  by  division, 
and  are  never  observed  to  originate  neogenetically.     The 
same    statement    holds    good    for    the    centrosomes,     for 
chlorophyll   corpuscles    and   for  various   kinds  of   chroma- 
tophores.      It  is  not  to  be  denied  that   these  facts,   which 
become  more  and  more  familiar  to  the  working  microscopist, 
appear    to    lend    a    powerful    support    to    the    theory    of 
biophors  ;  in  a  limited  sense  they  may  be  said  to  be  a  proof 
of  the    statement    that    the    cell    is    an     organised    body. 
Whether,  as  Wiesner  claims  to  be  the  case,  there  are  many 
other  constituents  of  cells  which  similarly  reproduce  their 
kind    by    division,    and    are   never    observed    to    originate 
independently,  may  for  the  present  be  left  out  of  considera- 
tion.     The  evidence   that  amylum  grains  and   granules  of 
various  kinds  behave  like  the  centrosomes  in  this  respect,  is 
as  yet  too  slight,  and  the  observations  are  too  conflicting  to 
enable  us  to  come  to  a  judgment   without  entering   into   a 
mass  of  detail  which  is  not  wholly  relevant  to  the  question 
at  issue.      But  there  is  at  least  one  criticism  which  is  worthy 
of  mention,  namely,  that  of  Biitschli,  who  points  out  {loc.  cit., 
p.  200)  that  among  the  strongly  staining  granules  of  proto- 
plasm there  are  bodies  which  are  not  actually  constituents 
of   the    protoplasm     but    are    symbiotic    micro-organisms. 
The  existence  of  such  organisms,  which  have  been  called 


no  SCIENCE  PROGRESS. 

Bacterolds,  has  been  frequently  demonstrated  in  animal 
and  vegetable  cells,  and  Biitschli  points  out  that  granules 
similar  in  appearance  to  bacteroids  occur  in  the  Vorticellinse 
and  may  be  observed  at  certain  times  to  be  in  a  state  of 
rapid  proliferation. 

Just  before  writing  these  pages  I  have  been  shown 
preparations  exhibiting  the  numerous  bacteria  symbiotic 
in  Pelomyxa,  and  it  is  very  possible  that  the  rapid 
proliferation  of  bacteroids  has  been  mistaken  by  various 
observers  for  the  reproductive  activity  of  granules  forming 
an  integral  part  of  the  cell.  It  is  almost  certain  that  the 
mistake  has  been  made  in  some  cases,  and  until  further 
investigation  has  increased  our  knowledge  of  the  various 
micro-organisms  which  are  symbiotic  or  parasitic  in  cells,  it 
is  well  to  be  somewhat  sceptical  of  statements  regarding 
the  divisional  processes  of  cell  contents.  It  would  seem  then 
that  our  present  knowledge  does  not  justify  our  regarding 
all  the  particles  of  a  cell  as  originating  in  a  similar  manner 
from  the  division  of  pre-existent  similar  particles,  though 
we  must  affirm  in  the  most  positive  manner  that  some  few 
of  the  constituents  of  the  cell  originate  in  this  way  only,  and 
are  never  produced  de  novo.  The  question  now  to  be 
considered  is  this :  must  we,  because  these  bodies  (the 
centrosomes,  chromosomes,  etc.)  assimilate,  grow  and 
reproduce  themselves  by  division,  regard  them  as  indepen- 
dent vital  units?  A  cell  exhibits  these  phenomena  and  the 
cell  is  regarded  as  an  independent  unit  in  posse,  if  not 
actually  in  esse ;  must  we  therefore  attribute  to  all  bodies 
exhibiting  the  same  phenomena  the  character  of  indepen- 
dent units  ?  The  answer,  I  believe,  is  very  decidedly  no. 
Cells  would  never  have  been  regarded  as  independent  units 
if  they  had  merely  been  observed  to  assimilate,  grow  and 
divide,  whilst  retaining  their  connection  with  other  cells 
undergoing  the  same  processes.  The  quotations  which 
I  have  given  from  Schwann's  work  show  that  the 
theory  that  the  cell  is  an  independent  life  unit  was  not 
founded  on  the  fact  that  it  assimilates,  grows  and  divides, — 
Schwann  indeed  overlooked  the  phenomena  of  reproduction 
by  division — but   upon    the   fact   that   cells  are  capable  of 


THE  PRESENT  POSITION  OF  CELL-THEORY,     in 

leading  an  independent  existence.  This  is  so  important  a 
part  of  the  cell-theory  that  I  may  again  quote  in  his  own 
words  Schwann's  reasons  for  calling  the  cell  an  elementary 
unit  of  life.  "  Now  if  we  find  that  some  of  these  elementary 
parts  not  differing  from  the  others  are  capable  of  separating 
themselves  from  the  organism  and  pursuing  an  independent 
growth,  we  may  thence  conclude  that  each  of  the  other 
elementary  parts  is  already  possessed  of  the  power  to  take 
up  fresh  molecules  and  grow,  and  that  therefore  each 
elementary  part  possesses  a  power  of  its  own,  an  indepen- 
dent life." 

In  the  case  which  we  are  considering  the  very  faculty 
which  was  so  powerful  a  reason  for  regarding  cells  as 
independent  units  is  wanting.  Nobody  has  ever  observed 
a  nucleus  or  a  centrosome  or  even  a  chromatophore  to 
separate  itself  from  the  cell  and  pursue  an  independent 
existence.  And  not  only  is  there  no  recorded  case  of  the 
constituent  particles  of  cells  separating  themselves  spon- 
taneously from  the  cell,  but  experiments  which  have  been 
made  with  the  express  purpose  of  determining  whether 
these  particles  can  live  apart  from  the  cell  to  which  they 
belong  have  in  every  case  given  a  negative  result.  Even 
the  nucleus,  highly  complicated  as  it  is,  and  itself  composed 
of  smaller  particles  which  may  easily  be  demonstrated, 
perishes  when  removed  from  the  cell  body.  The  chroma- 
tophores  similarly  perish,  and  so  no  doubt  would  the 
centrosomes  if  it  were  possible  to  isolate  such  very  minute 
particles.  Many  instances  might  be  cited  in  proof  of  this, 
but  it  is  scarcely  necessary  to  bring  forward  the  details  ; 
the  reader  can  obtain  them  by  reference  to  the  works  of 
Nussbaum,1  A.  Gruber  and  Verworn.2 

It  is  of  some  interest  in  this  connection  to  contrast  the 
process  of  reproduction  in  unicellular  and  multicellular  or- 
ganisms. In  the  latter  reproduction  is  effected  by  the 
separation  of  a   single  unit,  a  cell,  from  the  aggregate,  and 

1  M.  Nussbaum,  Biol.  Centralblatt,  vol.  iv. 

2  Max  Verworn,  "  Die  physiologische  Bedeutung  des  Zellkerns," 
Pfliiger  s  Archiv,  vol.  li.,  1892. 


ii2  SCIENCE  PROGRESS. 

the  unit  so  separated  has  from  the  time  of  its  separation  an 
independent  individuality  and  eventually  reproduces  the 
aggregate.  The  fact  that  the  union  of  two  cells  is  commonly 
necessary  for  the  maintenance  of  life  and  the  exhibition  of 
the  powers  of  development,  need  not  be  urged  as  an  objec- 
tion to  this  simple  statement  of  the  case,  for  the  facts  of 
parthenogenesis  show  that  the  union  of  two  cells  is  not  an 
essential  feature.  Now  if  we  adopt  Wiesner's  scheme,  and 
imagine  that  organisation  does  not  stop  at  the  cell,  but  that 
beyond  this  there  are  granules,  and  beyond  these  again 
plasomes,  and  that  the  plasomes  stand  in  the  same  relation 
to  the  cell  that  the  cell  stands  to  the  multicellular  organism  ; 
we  should  expect  to  find  that  in  the  reproduction  of 
monocytial  organisms  the  plasome  plays  a  part  anal- 
ogous to  that  played  by  the  cell  in  the  reproductive 
processes  of  polycytial  organisms.  But  we  find  nothing 
of  the  kind.  The  monocytial  organism  reproduces  itself  in 
just  the  same  way  as  the  polycytial,  by  the  separation  of  a 
cell,  complete  in  all  its  parts.  There  is  no  such  thing 
known,  even  in  cases  where  a  flagellate  or  a  radiolarian 
breaks  up  into  innumerable  particles  or  spores  of  extreme 
minuteness,  as  the  separation  of  any  one  individual  con- 
stituent of  a  cell  possessed  of  the  power  of  leading  an  in- 
dependent existence  and  in  time  of  reproducing  all  the  other 
constituents.  Every  spore,  however  minute,  has  its  portion  of 
the  cytoplasm  and  its  share  of  nuclear  matter.  If  there  are 
any  other  constituents,  it  probably  has  its  share  of  these 
also,  but  one  cannot  speak  with  certainty  on  this  point,  for 
positive  evidence  is  wofully  deficient.  At  any  rate  Wiesner, 
holding  fast  to  his  theory  that  nothing,  not  even  an  amylum 
or  an  aleurone  grain,  is  produced  neogenetically,  is  at  great 
pains  to  prove  that  in  cellular  reproduction  all  the  parts 
of  the  parent  are  transferred  to  the  offspring.  Assuming 
that  this  is  so,  and  remembering  that  there  is  abundant 
evidence  that  nuclear  matter  and  cytoplasm  are  always 
transferred,  it  is  evident  that  the  relation  in  which  the 
plasomes  or  biophors,  regarded  as  ultimate  vital  units, 
stand  to  the  cell,  is  not  at  all  the  same  as  the  relation  in 
which  the  cell,  regarded  as  an  ultimate  unit,  stands  to  the 


THE  PRESENT  POSITION  OF  CELL-THEORY.     113 

polycytial  organism.  Biitschli,  in  a  short  but  very  weighty 
sentence,1  brings  forward  the  same  argument  that  I  have 
just  used  in  opposition  to  Altmann's  theory  of  the  part 
played  by  granules  in  the  vital  processes  of  protoplasm.  In 
my  judgment  the  argument  as  far  as  it  goes  is  a  sound 
one,  but  I  am  aware  that  it  does  not  altogether  refute  the 
theory  of  biophors,  but  only  that  part  of  it  which  states  that 
as  cells  are  to  polycytial  aggregates  so  are  biophors  to  cells. 
This  refutation,  however,  seems  to  me  to  be  a  considerable 
gain.  For  it  enables  us  to  apprehend  that  the  structure  or 
constitution  of  the  cell,  whatever  it  may  be,  is  not  to  be  ex- 
pressed in  the  same  terms  as  the  structure  of  the  higher 
organisms. 

It  may  be  objected  that  nobody  does  express  the 
structure  of  the  cell  in  such  terms,  but  the  objection  does 
not  hold  good.  It  is  true  that  most  authors  are  more 
guarded  in  their  expressions  than  Wiesner,  and  evade  the 
responsibility  of  declaring  that  the  biophor  is  to  the  cell 
as  the  cell  is  to  the  polycytial  organism,  by  means  of  re- 
servations, couched  for  the  most  part  in  terms  so  ambiguous 
and  even  transcendental  that  the  whole  issue  is  involved  in 
an  obscurity  from  which  it  seems  hopeless  to  try  to  escape. 
But  these  expedients  are  really  of  little  use.  The  fact  re- 
mains that  in  every  case  the  fundamental  idea  is  the  same, 
that  the  phenomena  exhibited  by  isolated  cells  having  an 
independent  individual  existence  are  of  essentially  the  same 
kind  as  the  phenomena  exhibited  bypolycytial  organisms  and 
must  be  explained  on  the  same  grounds. 

If  it  be  not  so,  what  is  the  meaning  of  the  argument 
which  was  first  put  forward  in  definite  shape  by  Brlicke, 
and  has  been  repeated  by  every  author  who  attacks  the 
question  in  the  same  manner  that  he  did,   that  the  com- 

1  "  So  long  as  the  individual  constituents  of  the  cell  are  not  seen  to 
persist  when  isolated,  nor  are  distinct  living  phenomena  observed  in  them, 
it  is  very  dangerous  to  speak  of  their  life  as  something  which  they  possess 
in  themselves.  They  are  so  far  living,  as  long  as  the  opposite  is  not  proved, 
in  that  they  are  parts  of  living  organism,  so  that  the  granula  may  be 
living  in  the  same  way  as  the  nucleus,  even  though  they  no  longer  betray 
any  sign  of  life  after  isolation"  (Joe.  eit.,  p.  199). 

8 


ii4  SCIENCE  PROGRESS. 

plexity  of  the  phenomena  exhibited  by  individual  cells,  say 
by  an  amceba,  is  so  great,  the  functions  observed  are  so 
many  and  so  various  in  their  kind  that  they  can  only  be 
explained  by  the  assumption  that  protoplasm  is  an  organised 
body  ?  Taking  the  words  of  O.  Hertwig  as  a  fair  ex- 
pression of  current  opinions  on  the  life  processes  of  a  poly- 
cytial  organism,  "  that  the  aggregate  life  processes  of  a  com- 
posite organism  appear  to  be  nothing  more  than  the  ex- 
ceedingly complicated  result  of  the  individual  life  processes 
of  its  numerous  and  variously  functional  cells,"  it  is  evident 
that  to  the  minds  of  Briicke  and  his  successors  the  aggre- 
gate life  processes  of  the  corpuscle  of  protoplasm  called  a 
cell  are  nothing  more  than  the  highly  complicated  result  of 
the  individual  life  processes  of  its  numerous  and  variously 
functional  biophors.  If  they  do  not  mean  this,  I  am  quite 
at  a  loss  to  know  what  they  do  mean,  or  to  understand  the 
relevancy  of  the  so-called  axiom  laid  down  by  Whitman, 
that  "function  presupposes  structure,"  or  the  meaning  of 
the  statement  expressed  so  often  and  with  such  obvious 
satisfaction,  that  "  the  cell  is  an  organism  ".  These  sen- 
tences, so  terse  and  so  epigrammatic,  exercise  a  peculiar 
fascination  over  most  minds.  To  understand  their  exact 
applicability  to  the  question  at  issue  they  must  be  carefully 
examined.  Function  presupposes  structure.  To  the  bio- 
logist who  makes  a  rapid  mental  survey  of  his  experiences, 
this  appears  to  be  a  generalisation  of  universal  truth. 
Physiology,  which  draws  its  inferences  almost  exclusively 
from  the  study  of  the  higher  animals,  tells  us  that  ultimately 
every  function  of  the  composite  organism  is  to  be  referred 
to  a  particular  group  of  cells,  and  that  cells  differ  in  kind 
according  to  the  different  functions  which  they  exhibit.  So 
much  is  this  truth  forced  upon  us  that  if  conceivably  a  new 
function  were  to  make  its  appearance,  we  should  immediately 
search  for  the  cell  groups  appropriate  to  the  performance  of 
that  function.  So  far  so  good,  but  before  proceeding  further 
we  must  take  note  that  the  statement  that  function  pre- 
supposes structure  is  a  generalisation  founded  on  experience. 
It  is  not  an  axiom  as  Whitman  calls  it,  for  an  axiom  is  a 
proposition  which  is  self-evident,  and  this  assuredly  is  not. 


THE  PRESENT  POSITION  OF  CELL-THEORY.     115 

The  next  step  is  to  transfer  this  generalisation,  founded  on 
experience,  into  a  new  region,  to  the  functions  of  cells.  In 
order  to  do  this  we  should  possess  the  same  experiences 
with  regard  to  the  functions  of  cells  which  we  possess 
with  regard  to  the  functions  of  composite  organisms.  But 
these  experiences  are  entirely  wanting.  We  observe  that 
protoplasm  exhibits  functions,  that  it  assimilates,  that  it  is 
irritable,  that  it  is  contractile,  that  it  is  reproductive,  and  so 
forth  ;  but  who  has  been  able  to  demonstrate  or  even  to 
suggest  with  any  plausibility  that  there  are  structures 
specially  devoted  to  assimilation,  to  contractility,  to  irrit- 
ability, and  to  reproduction  in  protoplasm?  It  is  evident 
that  the  absence  of  any  such  experiences  has  been  felt  by 
many  observers,  who  have  accordingly  studied  protoplasm 
with  a  view  to  finding  the  required  structures,  and  some 
are  inclined  to  say  that  the  nucleus  or  perhaps  the  centro- 
some  is  reproductive,  the  amylum  and  aleurone  bodies  are 
assimilative  and  so  forth.  But  there  are  protozoa  endowed 
with  active  functions  which  have  no  centralised  nucleus  ; 
the  presence  of  centrosomes  has  yet  to  be  demonstrated  in 
protozoa  in  general,  and  there  are  forms  in  which,  as 
Biitschli  well  points  out,  the  protoplasm  is  homogeneous, 
e.g.,  in  the  pseudopodia  Gromia  dujardini}  The  reader 
should  refer  to  Biitschli's  work  for  a  discussion  of  the  sub- 
ject of  hyaline  protoplasm  (loc.  cit.,  p.  262).  The  fact  that 
it  exists  is  of  the  highest  importance,  for  it  shows  that  there 
is  living  substance  exhibiting  the  usual  vital  phenomena  of 
assimilation,  contractility,  etc.,  which,  nevertheless,  defies 
all  attempts  to  recognise  an  organisation  which  in  the  light 
of  previous  experience  would  seem  adequate  to  the  effects 
produced,  and  it  shows  also  that  the  centrosomes,  the 
amylum  grains,  and  their  analogues,  and  the  whole  category 
of  granules    are    secondary    phenomena,    which    may    be 

1  Not  only  are  there  no  granules  in  homogeneous  protoplasm,  but  the 
alveolar  structure  of  it  is  unrecognisable.  It  is  easily  shown,  however,  that 
the  homogeneous  substance  is  produced  from  alveolar  protoplasm  and  is 
capable  of  reconversion  into  it.  The  physical  explanation  of  the  dis- 
appearance of  the  alveolar  structure  is  given  by  Biitschli  on  p.  264  of  the 
English  translation  of  his  work. 


n6  SCIENCE  PROGRESS. 

altogether   absent   and    yet    the   life  processes   go  on  un- 
changed. 

It  must  be  confessed  then,  that  the  experiences  which 
so  amply  justified  our  generalisation  when  applied  to  com- 
posite organisms  are  altogether  lacking  when  we  seek  for 
a  justification  for  applying  it  to  the  simplest  unicellular 
organisms.  Moreover  I  have  just  shown  that  in  one  im- 
portant particular  at  least,  we  do  not  merely  lack  these 
experiences,  but  that  we  have  experiences  of  an  entirely 
different  kind.  In  face  of  this  is  it  not  obvious  that  the 
captivating  generalisation  must  be  abandoned  altogether  in 
the  region  which  we  are  now  discussing  ?  For  it  is  founded 
on  experience,  and  where  experience  fails  or  is  contradictory 
the  generalisation  fails  also. 

After  what  has  already  been  said  it  is  unnecessary  for 
me  to  enter  into  a  detailed  examination  of  the  other  state- 
ment which  is  considered  to  mark  a  great  advance  in  bio- 
logical thought,  that  "the  cell  is  an  organism".  It  is 
sufficient  to  say  that  if  this  proposition  means  anything  at 
all,  it  means  that  the  cell  has  an  organisation  which  is 
similar  in  kind  to  that  of  a  composite  organism  of  which  a 
cell  is  a  part.  If  I  am  told  that  it  does  not  mean  this,  but 
something  else,  then  I  ask,  firstly,  what  does  it  mean  ?  And, 
secondly,  if  it  does  not  mean  this,  what  necessity  is  there  for 
assuming  that  the  protoplasm  of  the  cell  is  built  up  of  bio- 
phors,  the  biophor  being  the  elementary  living  constituent, 
assimilating,  growing  and  dividing,  taking  up  definite  posi- 
tions in  the  cell,  combining  with  others  like  or  unlike  itself  to 
form  higher  aggregates,  and  so  impressing  a  fixed  archi- 
tecture on  the  cell  of  which  it  is  a  component  ?  Why,  in 
short,  if  the  statement  does  not  mean  that  the  organisation 
of  the  cell  is  the  same  in  kind  as  the  organisation  of  a 
composite  animal,  why  then  does  everybody  who  believes 
that  the  cell  is  an  organism  ascribe  to  it  an  organisation 
which  is  the  same  in  kind  as  that  of  the  higher  animals  ? 

The  fact  is,  and  it  is  patent  to  everybody,  that  most 
authors  do  conceive  of  the  cell-organisation  as  being  the 
same  in  kind  as  the  organisation  of  higher  animals.  They 
either  have  the  courage   of  their    opinions,  like   Wiesner, 


THE  PRESENT  POSITION  OF  CELL-THEORY.     117 

and  say  so  in  so  many  words,  or  they  tacitly  admit  it  by 
their  description  of  what  they  conceive  cell-organisation  to 
be.     They  are  dominated  by  the  cell-theory.      Mr.   Adam 
Sedgwick  has  recently  said  that  the  cell-theory  is  an  incubus 
which  perverts  the  minds  of  biologists,  whose  minds  are  so 
saturated  with  conceptions  borrowed  from    the  cell-theory 
that    they  are  unable  to  see  anything  else.      I  have  else- 
where found  fault  with  this  statement,  but  when  the  theories 
of  cell-organisation  are  considered,    I    must  freely  confess 
that  he  has  right  on  his  side.      Not  only  does  the  zoologist 
believe   "that  the  cell  is  the  unit  of  structure,  and  that  it 
forms  the  basis  of  organisation  in  the  metazoa,"  but  he  also 
believes  that  some  correlative  of  the    cell  forms  the  basis 
of  all  organisation  whatsoever.      His  eyes  are   "  blinded  to 
the  most  patent  facts"  by  ideas  derived  from  the  cell-theory, 
and  it  is  not  too  much  to  say  that  the  theory  does  "  obstruct 
the  way  of  real   progress  in  the  knowledge  of  structure  ". 
Whether  consciously  or  unconsciously  the  believer  in  bio- 
phors   starts  with   ideas   derived   from   the    cell-theory,  he 
tacitly  assumes  the  universal  applicability  of  the  proposition 
that  function  presupposes  structure,  and  he  seeks  to  explain 
the  functions  of  protoplasm  by  attributing  to  it  an  organisa- 
tion which  in  all  essential   characters  is  the  equivalent  of 
the  organisation  of  the  metazoa.     Since  I  have  just  shown 
that  there  is  no  justification  for  transferring  a  generalisation 
based  upon   experience  to  a  region  in  which  experience  is 
either  wholly  wanting  or,  if  present,  of  a  different  kind,  it  is 
hardly  necessary  for  me  to  elaborate  and  show  that  it  is 
equally  unjustifiable  to  attribute  to  the  unknown  a  plan  of 
organisation  identical  in  kind  with  the  plan  which  we  have 
learnt  by  experience   to  recognise   as   the  attribute  of  the 
known. 

Some  time  ago  I  pointed  out  that  there  was  a  fallacy  in 
the  word  organism.1  Whitman  has  ridiculed  the  statement, 
yet  the  more  I  reflect  upon  it  the  more  I  am  convinced 
that  the  fallacy  exists,  and  that  it  is  in  the  highest  degree 
mischievous  and   misleading.       By  an  organism  we  mean 

1  G.  C.  Bourne,  "  Epigenesis  and  Evolution,"  this  journal,  vol  i.,  1894. 


n8  SCIENCE  PROGRESS. 

either  an  independent  living  thing,  in  which  case  the  term 
is  loose  but  applicable  to  every  animal  in  the  monocytial 
stage,  or  we  mean  a  thing  possessing  organisation,  and  by 
organisation  we  mean  a  certain  structural  plan,  the  idea  of 
which  is  a  generalisation  from  our  experience  of  animal  and 
vegetable  structure  in  general.      That   this   is   historically 
and  in  fact  the  connotation  of  the  term  organisation  is  in- 
dubitable.1      When    we    use    the    term    organisation    we 
either  use  it  in  this  connotation  or  in  some  other.      If  we 
use  it  in  the  same  connotation  with  respect  to  protoplasmic 
structure,  we  are  consistent,  but,  as   I   have  shown,   we  are 
applying    ideas    derived   from    one    set    of   phenomena    to 
another  set  of  phenomena  to  which  they  are  not  appropriate. 
But  if  we  use  it  with  another  connotation,  then  we  expose 
ourselves  at  once  to  the  risk  of  the  well-known  fallacy  which 
is  inseparable  from  the  use  of  the  same  term  with  different 
connotations.      If  the  two  connotations  are  clearly  defined 
and    generally    understood,    the    fallacy    may    be   avoided, 
though  the  inconvenience  remains  ;  but  if  the  one  connota- 
tion   is   clear  and  definite  whilst   the  other  is   vague  and 
ambiguous   in   the   highest  degree,   no  amount  of   circum- 
spection will  prevent  our  falling  into  the  fallacy  almost  at 
the  first  opportunity.     This  is  exactly  the  case  with  the  term 
organisation.      In  the  one  sense  we  know  its  connotation 
exactly,  and  when  authors  use  it  in  that  sense  they  have, 
in  the  course  of  their  arguments,  to  adhere  strictly  to  the 
technical  sense  of  the  word.       Most  of  them  do  this,  for 
they  are  aware  of  the  absurdities  and  inconsistencies  into 
which  they   would  fall   if  they  did  otherwise.      But   what 
of  those  who  use  the  term  with  another  connotation  ?    They 
assure  us  that  it  does  not  denote  a  plan  of  structure  like  in 
kind   to  that  of  the   metazoa  :  what  then    does    it  denote  ? 
Something  so  vague,  so  unreal  and  unsubstantial  that  we 

1  Thus  in  Worcester's  Dictionary  of  the  English  Language,  1881  : — 
Organisation.  The  condition  of  an  organised  body  or  the  totality  of 

parts  which  constitute  and  the  laws  which  regulate  an  organised  body. 

Organised.  Formed  with  organs  :  composed  of  several  individual  parts 

or  organs,  each  of  which   has  its  proper  function  and  conduces    to  the 

existence  of  the  entire  system. 


THE  PRESENT  POSITION  OF  CELL-THEORY.     119 

are  even  at  a  loss  to  know  to  what  to  apply  it ;  its  connota- 
tion has  never  even  been  attempted.  The  futility  of  using  a 
term  without  connotation  and  with  the  most  vague  denotation 
is  so  well  illustrated  by  the  following  passage  from  Whit- 
man that  I  cannot  refrain  from  introducing  it  here  :  "  When 
we  speak  of  the  organisation  of  the  germ  as  cut  directly 
from  a  pre-existing  parental  organisation  of  the  same  kind 
we  are  not  thinking  of  the  definitive  organisation  which 
belongs  to  the  fully  formed  organism,  but  of  that  primary 
organisation  which  belongs  to  the  protoplasm  itself".  This 
raises  our  expectations,  we  are  going  to  hear  something  of 
the  primary  organisation  which  belongs  to  protoplasm  itself. 
Whitman  continues:  "We  are  so  accustomed  to  connect 
the  idea  of  organisation  with  the  anatomical  organs  of  the 
adult  that  we  are  apt  to  forget  that  there  is  a  primary 
organisation  which  underlies  every  anatomical  organ.  The 
germ  has  this  primary  organisation  ;  it  is  therefore  an 
organism,  and  as  such  may  dominate  its  own  development." 
From  which  weighty  and  sententious  passage  we  gather 
that  the  germ  is  an  organism  because  it  has  a  primary 
organisation  which  is  not  the  definitive  organisation  which 
belongs  to  the  fully  formed  organism,  but  a  primary  organ- 
isation which  belongs  to  protoplasm  itself.  What  on  earth, 
we  may  well  ask,  is  this  primary  organisation  ?  The 
answer  is  given  on  the  same  page.  It  is  "that  original 
constitution  of  the  germ  which  pre-determines  its  type  of 
development  and  the  form  which  ultimately  distinguishes  it 
from  other  species  developing  under  like  external  conditions". 
The  terms  "original  constitution"  and  "primary  organisa- 
tion "  are  merely  synonyms.  So  we  learn  that  the  primary 
organisation  so  important  to  those  who  have  more  thought- 
fully scanned  the  gap  between  the  cell  and  the  physical 
molecule,  is  the  primary  organisation  of  the  germ,  which 
pre-determines  its  type  of  development,  etc.  I  hope  that 
others  are  satisfied  by  this  most  remarkable  piece  of 
scientific  exposition.  For  myself  I  must  humbly  confess 
that  I  am  none  the  wiser  for  it,  any  more  than  I  should  be 
if  I  asked  what  was  a  Megalosaurus  and  I  was  told  :  "A 
Megalosaurus,  why  you  know  it  is  a  big  lizard,  it  is — a — a 


120  SCIENCE  PROGRESS. 

Megalosaurus  in  fact ".  Nor  is  confusion  less  when  I  am 
told  in  one  sentence  that  the  organisation  of  the  germ  cut 
directly  from  pre-existing  parental  organisation  of  the  same 
kind  is  not  the  definitive  organisation  which  belongs  to  the 
fully  formed  organism,  but  is  that  primary  organisation 
which  belongs  to  protoplasm  itself,  and  I  read  in  the 
sentence  immediately  preceding  that  "  the  essential  thing  is 
not  simply  continuity  of  germ  substance  of  the  same 
chemico-physical  constitution,  but  actual  identity  of  germ- 
organisation  with  stirp-organisation  ".  The  organisation  of 
the  germ  is  identical  with  the  organisation  of  the  stirp,  and 
yet  the  organisation  of  the  germ  is  not  that  of  the  fully 
formed  organism,  but  is  a  primary  organisation  which 
belongs  to  protoplasm  itself.  What  does  it  all  mean  ?  It  is 
different  and  yet  it  is  identical,  and  it  is  organisation,  organisa- 
tion, toujours  organisation.  I  beg  Dr.  Whitman,  for  pity's 
sake,  to  descend  from  his  altitude,  scarcely  dreamed  of  in  the 
philosophy  of  Harvey  and  Wolff,  and  to  condescend  to 
inform  a  poor  bewildered  mortal,  who  confesses  to  a  pre- 
judice in  favour  of  things  which  he  can  understand,  what 
this  wonderful  primary  organisation  is. 

Seriously  speaking  I  believe  that  organisation  either 
means  a  plan  of  structure  of  the  same  type  as  the  structure 
of  higher  animals  and  plants,  and  capable  of  being  described 
in  intelligible  terms  as  it  has  been  by  Weismann,  Wiesner 
and  others,  or  it  means  nothing  at  all  ;  it  is  a  mere  phrase 
which  seeks  to  cover  but  does  not  conceal  our  ignorance. 

G.  C.   Bourne. 
( To  be  continued. ) 


SOLID    SOLUTIONS. 

IF  we  define  solutions  as  homogeneous  mixtures  of  sub- 
stances in  variable  proportions,  we  are  at  once  obliged 
to  admit  the  existence  of  solid  solutions,  for  there  are  many 
mixed  solids  which  fulfil  the  requirements  of  this  definition. 
Common  potash  alum,  for  example,  can  crystallise  together 
with  ammonia  alum,  and  form  mixed  crystals  which  are 
perfectly  homogeneous  and  of  the  same  composition  through 
out,  although  the  proportions  of  the  two  constituents  may 
be  varied  at  will  by  proper  selection  of  the  aqueous  solution 
from  which  the  crystals  separate. 

We  are  inclined,  however,  to  look  in  solutions  for  some- 
thing more  than  mere  homogeneity  and  uniformity  of  com- 
position, and  perhaps  one  of  the  most  obvious  characters  of 
a  liquid  solution  is  this,  that  should  it  at  first  be  of  different 
composition  in  different  parts  of  its  mass,  there  is  always 
present  the  tendency  of  the  dissolved  body  to  attain  a  uni- 
form distribution  throughout  the  solvent.  The  process  of 
equalisation  of  the  composition,  or  diffusion,  occurs  in  all 
solutions  which  are  more  concentrated  in  one  part  than  in 
another,  the  dissolved  substance  moving  from  the  place  of 
greater  to  the  place  of  less  concentration.  Diffusion  in 
solution  goes  forward  very  slowly  if  the  liquid  is  protected 
from  mechanical  disturbance  and  sudden  change  of  tem- 
perature, months  being  requisite  for  the  attainment  of  uni- 
form concentration  if  a  comparatively  short  column  of  pure 
solvent  is  placed  above  a  denser  layer  of  strong  solution 
contained  in  the  bottom  of  a  cylinder.  If  diffusion  takes 
place  in  solids  we  might  expect  it  to  proceed  even  more 
slowly. 

A  class  of  substances  which  form  in  some  sort  a  connect- 
ing link  between  liquids  and  solids,  and  are  specially  suited 
to  the  study  of  diffusion  phenomena,  is  to  be  found  in  jellies. 
Graham,  to  whom  we  owe  our  first  exact  knowledge  of 
diffusion  in  liquids,  prepared  a  stiff  jelly  containing  common 
salt  in  solution  in  one  part,  and  compared  the  rate  at  which 


122  SCIENCE  PROGRESS. 

the  salt  diffused  in  it  with  the  rate  at  which  salt  dif- 
fused in  pure  water.  He  found  that  the  diffusion  in  the 
jelly  took  place  almost,  if  not  quite,  as  fast  as  in  water 
itself.  The  composition  of  the  jelly  was  2  per  cent,  gelose 
and  98  per  cent,  water,  so  that,  as  far  as  actual  substance 
was  concerned,  the  salt  had  to  meet  practically  the  resistance 
of  water  alone  in  both  cases,  and  the  experiment  showed 
that  the  mere  change  in  apparent  condition  of  the  whole 
mass  had  little  or  no  influence  on  the  rate  of  diffusion. 
Subsequent  experiments  have  served  to  confirm  Graham's 
results. 

When  we  pass  to  solids  proper  we  find  that  instances 
are  not  wanting  of  what  is  apparently  diffusion  within  them. 
Van't  Hoff  in  his  fundamental  paper  on  solid  solutions  gives 
numerous  examples.  In  the  preparation  of  steel  by  the  cem- 
entation process  bars  of  wrought  iron  are  packed  in  charcoal 
and  subjected  to  a  red  heat  for  several  days.  The  charcoal 
gradually  penetrates  the  iron  and  converts  it  into  steel.  It 
matters  little  for  our  purpose  what  the  particular  form  is  that 
the  carbon  assumes  during  its  passage  through  the  iron — in 
some  fashion  or  other  it  reaches  the  centre  of  the  dense  bar. 
The  distribution  of  the  carbon,  too,  if  the  operation  is  inter- 
rupted before  uniformity  has  been  attained,  is  precisely  what 
would  be  expected  if  the  phenomenon  were  one  of  real  diffu- 
sion ;  and  the  influence  of  time  is  the  same  in  both  processes. 
Not  only  has  carbon  been  observed  to  pass  through  iron, 
but  it  has  even  been  proved  to  travel  slowly  through  por- 
celain, when  porcelain  crucibles  have  been  heated  in  a  bed  of 
graphite. 

When  a  metal  such  as  copper  is  deposited  galvanically 
on  another  metal,  it  penetrates  beyond  the  surface  of  the 
latter  into  its  substance,  and  zinc  objects  which  have  been 
lightly  coppered  are,  even  when  protected  by  a  coating  of 
varnish,  occasionally  observed  to  become  white  again 
owing  to  the  gradual  mixing  of  the  two  metals  near  the 
surface. 

Professor  Spring,  of  Liege,  who  has  devoted  special 
attention  to  the  chemical  behaviour  of  solids  under  high 
pressure,  has  supplied  some  interesting  instances  of  pheno- 


SOLID  SOLUTIONS.  123 

mena  which  can  only  be  explained  by  the  assumption  of 
solid  solutions.  When  equivalent  proportions  of  barium 
sulphate  and  sodium  carbonate  are  finely  powdered, 
intimately  mixed,  and  subjected  to  a  very  high  pressure,  a 
double  decomposition  takes  place  with  formation  of  barium 
carbonate  and  sodium  sulphate.  The  decomposition,  how- 
ever, is  not  complete,  only  20  per  cent,  of  the  original 
substances  being  transformed.  If,  on  the  other  hand,  we 
start  with  a  mixture  of  barium  carbonate  and  sodium 
sulphate  and  compress  it,  we  find  that  the  reverse  trans- 
formation now  occurs,  barium  sulphate  and  sodium  carbonate 
being  formed,  and  that  to  the  extent  of  So  per  cent,  of  the 
original  substances  present.  Here  we  are  evidently  dealing 
with  a  state  of  equilibrium  between  the  four  substances 
above  mentioned,  which  can  only  exist  together  permanently 
under  pressure  in  certain  definite  proportions.  If  these 
proportions  are  departed  from,  the  system  so  transforms 
itself  that  the  requisite  state  for  equilibrium  is  attained. 
Now  this  of  itself  points  to  the  substances  existing  here  in 
a  state  analogous  to  that  of  bodies  in  liquid  solution,  for  we 
know  that  in  general  definite  proportions  are  necessary  in 
solutions  for  stable  equilibrium  to  exist.  In  the  case  of 
solids  the  general  rule  is  that  when  they  are  in  equilibrium 
under  given  conditions  in  one  proportion,  they  are  in 
equilibrium  under  the  same  conditions  in  every  other  pro- 
portion. The  behaviour,  then,  of  these  solids  under  pressure 
is  analogous  to  the  behaviour  of  substances  in  solution,  and 
different  from  the  ordinary  behaviour  of  solids.  The  con- 
tinuance of  the  pressure  is  not  essential  to  the  establishment 
of  such  a  definite  solid  equilibrium,  for  Spring  has  shown 
that  by  relieving  the  pressure  after  73  per  cent,  of  a 
system  of  barium  carbonate  and  sodium  sulphate  had  been 
transformed,  the  process  continued,  though  less  rapidly, 
and  after  a  week  had  reached  the  proportion  of  80  per  cent, 
necessary  for  equilibrium.  Here  diffusion  must  have  played 
a  part,  for  no  matter  how  finely  divided  the  reacting  sub- 
stances originally  were,  their  surface  of  contact  (where  alone 
the  mutual  decomposition  could  take  place  if  there  were  no 
diffusion)  must  have  been  comparatively  small. 


124  SCIENCE  PROGRESS. 

It  is  well  known  that  some  metals  have  the  property  of 
allowing  certain  gases  to  pass  through  them  under  favourable 
conditions,  the  most  thoroughly  investigated  instance  of 
this  kind  being  the  permeability  of  the  metal  palladium  to 
gaseous  hydrogen  at  moderately  high  temperatures.  At 
about  300°  C.  hydrogen  can  pass  quite  freely  through  a 
palladium  septum,  and  it  is  difficult  to  conceive  the  nature 
of  this  phenomenon  without  admitting  the  existence  of 
diffusion  in  the  solid.  Whether  the  hydrogen  is  dissolved 
in  the  palladium  or  forms  a  compound  with  it,  as  has  been 
asserted,  is  of  little  consequence,  for  in  the  latter  case  the 
compound  superficially  produced  must  have  possessed  the 
power  to  penetrate  the  remaining  metal,  or  to  allow  of  the 
passage  of  hydrogen  through  itself. 

Connected  with  the  process  of  diffusion  in  solution  we 
have  the  phenomena  of  the  conduction  of  electricity  in 
solutions,  or  electrolysis.  Here  the  electric  current  is 
carried  by  material  particles,  and  the  resistance  that  these 
experience  in  their  passage  through  the  solution  is  of  the 
same  nature  as  the  resistance  offered  to  diffusion.  Helm- 
holtz,  in  his  Faraday  lecture,  drew  attention  to  the  fact  that 
glass  behaves  as  an  electrolyte  towards  an  electric  current, 
i.e.,  that  the  current  in  passing  through  the  glass  is  as- 
sociated with  two  currents  of  particles  moving  in  opposite 
directions.  The  particles  travelling  towards  the  negative 
pole  of  the  battery  have  since  been  proved  to  move  faster 
than  those  moving  towards  the  positive  pole.  Lehmann 
also  has  shown  that  when  two  silver  electrodes  are  immersed 
in  fused  iodide  of  silver,  which  is  afterwards  allowed  to 
solidify,  and  a  current  of  electricity  is  passed  through  the 
solid  iodide,  one  of  the  electrodes  increases  in  weight  at  the 
expense  of  the  other,  and  that  the  phenomenon  can  be 
reversed  by  reversing  the  current. 

These  examples  will  suffice  to  indicate  that  we  are  not 
without  data  to  establish  an  analogy  between  the  behaviour 
of  certain  solids  and  the  behaviour  of  ordinary  liquid  solu- 
tions. Since  the  appearance  of  van't  Hoff's  original  paper 
on  the  subject  a  considerable  number  of  researches  have 
been  published  more  or  less  directly  bearing  on  the  question, 


SOLID  SOLUTIONS.  125 

but  the  results  achieved  have  on  the  whole  been  small,  owing 
chiefly  to  the  experimental  difficulties  encountered. 

An  important  application  of  the  idea  of  solid  solutions 
was  made  by  van't  Hoff  in  explaining  the  abnormalities 
that  are  sometimes  met  with  in  the  determination  of  mole- 
cular weights  by  the  lowering  of  the  freezing-point  in  solu- 
tions. It  had  been  proved  theoretically  that  the  freezing- 
point  of  a  given  solvent  should  be  depressed  to  a  certain 
value  (calculable  from  the  freezing-point  and  the  latent 
heat  of  fusion  of  the  solvent)  when  the  solution  was  of 
normal  concentration,  i.e.,  contained  one  gram-molecule 
of  dissolved  substance  per  litre.  The  nature  of  the  dis- 
solved substance  should  be  without  influence  on  this  value. 
Now,  whilst  it  was  ascertained  experimentally  that  this 
theoretical  relation  was  in  the  vast  majority  of  cases  ac- 
curately fulfilled,  yet  there  remained  certain  combinations 
of  dissolved  substance  and  solvent  which  gave  values  of  the 
depression  constant  altogether  at  variance  with  the  cal- 
culated value.  Thus,  metacresol  dissolved  in  phenol  gave 
a  depression  of  48  instead  of  74,  and  thiophene  dissolved  in 
benzene  a  depression  of  34  instead  of  53.  Van't  Hoff's 
explanation  of  these  and  similar  abnormally  low  values  of 
the  depression  was  that  the  freezing-point  observed  was  not 
in  the  strict  sense  the  freezing-point  which  had  been  assumed 
in  the  theoretical  reasoning.  The  true  freezing-point  of  a 
solution  is  the  temperature  at  which  the  liquid  is  in  equi- 
librium with  the  solid  solvent.  The  freezing-point  of  an 
aqueous  salt  solution,  for  example,  is  the  temperature  at 
which  it  can  exist  in  contact  with  pure  ice  without  the  ice 
melting  or  without  fresh  ice  being  deposited  from  the  solu- 
tion. Now,  in  the  exceptional  cases  above  alluded  to  it  is 
known  that  the  solid  and  the  solvent  have  a  tendency  to 
crystallise  together,  i.e.,  to  form  mixed  crystals,  so  that  the 
substance  that  separates  out  is  not  the  pure  solvent  but 
rather  a  solid  solution.  The  temperature  at  which  such  a 
solid  solution  would  be  in  equilibrium  with  the  liquid  solu- 
tion might  not  by  any  means  be  the  freezing-point  of  the 
solution  as  above  defined.  The  apparent  observed  freezing- 
point  of  the  solution,  therefore,  would  not  in  general  coincide 


126  SCIENCE  PROGRESS. 

with  the  calculated  depression,  and  van't  Hoff  from  theo- 
retical considerations  showed  how  the  divergence  could  be 
estimated  from  a  knowledge  of  the  composition  of  the  solid 
which  actually  separated  out  from  the  solution  on  cooling. 
That  the  abnormal  values  for  the  points  of  solidification 
depend  on  the  separation  of  the  dissolved  substance  along 
with  the  solvent  has  now  been  experimentally  verified  in  a 
considerable  number  of  cases.  Heycock  and  Neville  found 
that  for  the  case  of  solutions  of  antimony  in  molten  tin,  the 
freezing-point  of  the  tin  was  raised  instead  of  lowered  by 
the  presence  of  the  second  metal.  Kiister  has  shown  that 
this  and  similar  instances  are  susceptible  of  a  very  simple 
explanation.  The  two  metals  separate  out  together  in  very 
nearly  the  same  proportion  as  that  in  which  they  remain 
behind  in  the  liquid,  so  that  the  solution  solidifies  as  a 
whole.  In  such  circumstances  the  point  of  solidification  of 
the  liquid  can  be  calculated  by  the  simple  mixing  formula. 
If  the  melting-point  of  each  pure  substance  is  multiplied  by 
the  proportion  in  which  it  exists  in  the  mixture,  the  sum  of 
the  two  numbers  thus  obtained  will  give  the  point  of  solidi- 
fication of  the  solution.  As  antimony  melts  200  degrees 
higher  than  tin,  the  admixture  of  the  former  in  however 
small  proportion  will,  since  the  mixture  freezes  as  a  whole, 
raise  the  point  of  solidification  instead  of  lowering  it,  as 
would  be  the  case  if  pure  solid  tin  separated  from  the  liquid 
on  cooling. 

Not  only  do  solutions  exhibit  a  lower  freezing-point  than 
that  of  the  pure  solvent,  but  they  also  exhibit  a  lower 
vapour  tension.  The  pressure  of  aqueous  vapour  over 
salts  containing  water  of  crystallisation  may  in  many  cases 
be  measured  with  accuracy,  and  there  it  is  found  that  the 
isomorphous  admixture  of  another  salt  lowers  the  vapour 
pressure  of  water  which  is  in  equilibrium  with  the  solid. 
Thus  the  vapour  tension  of  a  mixed  crystal  of  ordinary  alum 
with  iron  alum  is  less  than  the  vapour  tension  of  either  of 
its  components.  In  this  respect  then  the  mixed  crystal 
behaves  as  a  solid  solution.  Again,  the  solubility  of  a  sub- 
stance is  diminished  when  it  itself  acts  as  a  solvent  for 
another  substance  insoluble  in  the  original  solvent.     Of  the 


SOLID  SOLUTIONS.  127 

three  liquids,  ether,  water,  and  benzene,  ether  and  water  are 
partially  miscible,  benzene  and  water  are  immiscible,  and 
ether  and  benzene  miscible  in  all  proportions.  Suppose  we 
take  water  as  the  original  solvent — then  on  shaking  it  up 
with  ether  we  find  that  the  latter  dissolves  to  a  certain 
definite  extent  in  it,  i.e.,  possesses  a  certain  solubility 
in  water.  If  now  we  previously  dissolve  benzene  in  the 
ether  which  we  shake  up  with  the  water,  we  find  that  the 
water  will  now  take  up  less  ether  than  before.  The  solu- 
bility of  ether  in  water  is  thus  diminished  when  benzene  is 
dissolved  in  it — and  this  behaviour  is  characteristic  of  all 
such  combinations  of  substances. 

A  case  of  this  kind  where  two  solids  play  the  part  of  the 
ether  and  benzene  in  the  previous  instance  has  been 
thoroughly  studied  by  F.  W.  Klister.  The  solid  hydrocarbon 
naphthalene  is,  like  the  hydrocarbon  benzene,  insoluble  in 
water ;  /3-naphthol,  on  the  other  hand,  is,  like  ether, 
sufficiently  soluble  in  water  to  permit  of  accurate  estimation. 
But  naphthalene  and  /3-naphthol  can  crystallise  together  in 
any  proportion  so  as  to  form  a  complete  series  of  isomor- 
phous  mixtures,  the  melting-points  of  which  vary  according 
to  the  rule  given  above  for  mixtures  of  antimony  and  tin. 
A  comparison  of  the  amount  of  /3-naphthol  dissolved  by  a 
given  quantity  of  water  from  such  mixtures  led  to  some- 
what unexpected  results.  Instead  of  the  addition  of  a 
small  quantity  of  naphthalene  to  /3-naphthol  lowering  the 
solubility  of  the  latter  in  water,  it  was  found  that  mixtures 
containing  as  much  as  30  per  cent,  of  naphthalene  had 
precisely  the  same  solubility  as  /3-naphthol  itself.  As  more 
naphthalene  was  added  the  solubility  increased  slightly, 
afterwards  to  diminish  continuously  to  zero  as  the  mixture 
was  made  to  contain  more  and  more  naphthalene.  The 
explanation  of  this  behaviour  suggested  by  Klister  is  that 
naphthalene  and  /3-naphthol  are  capable  of  forming  a  chemi- 
cal compound  consisting  of  one  molecule  of  each  substance, 
this  compound  being  decomposable  by  water,  an  assumption 
by  no  means  improbable,  as  many  similar  cases  have  been 
observed.  If  we  allow  further  that  the  solubility  of  the 
compound  is   greater  than  the  solubility  of  /3-naphthol,  the 


128  SCIENCE  PROGRESS. 

results  are  satisfactorily  accounted  for.  The  diminution 
of  solubility  when  much  naphthalene  is  present  is  the 
normal  depression  of  the  solubility  of  the  compound  by 
the  addition  of  excess  of  naphthalene.  The  solubility 
greater  than  that  of  pure  naphthol  is  the  solubility  of  the 
compound  naphtholnaphthalene.  The  constant  solubility 
(equal  to  that  of  /3-naphthol)  observed  when  there  is  little 
naphthalene  in  the  mixture  is  the  solubility  of  /3-naphthol, 
for  the  naphthalene  in  the  mixture  is  in  the  form  of  the 
compound  naphtholnaphthalene,  which  is  decomposed  at 
the  surface  by  water  into  naphthalene  and  /3-naphthol, 
which  exist  now  alongside  of  each  other  and  not  in  the 
intimate  union  of  a  crystalline  isomorphous  mixture. 

In  connection  with  the  results  of  these  experiments 
Klister  is  inclined  to  make  a  distinction  between  crystalline 
isomorphous  mixtures  and  solid  solutions  proper,  because  in 
the  former  there  is  practically  no  diffusion  owing  to  what 
may  be  termed  the  rigidity  of  the  crystalline  structure. 
He  admits,  however,  that  no  absolutely  sharp  line  can  be 
drawn,  as  there  are  various  intermediate  degrees  in  which 
diffusion  may  take  place.  A  reference  to  the  examples  of 
diffusion  in  solids  previously  cited  in  this  paper  will  show 
that  they  all  occur  in  amorphous  bodies  without  any  regular 
structure. 

A  point  of  considerable  interest  in  the  theory  of  solid 
solutions  is  that  it  affords  us  the  possibility  of  determining 
molecular  weights  of  the  dissolved  substances,  and  since  in 
isomorphous  mixtures  we  usually  attribute  similarity  of 
molecular  structure  to  the  two  components,  we  can  also  in 
this  case  form  an  estimate  of  the  molecular  weight  of  the 
solid  solvent.  From  his  experiments  on  the  amount  of  /3- 
naphthol  dissolved  by  water  from  mixtures  of  that  substance 
with  naphthalene,  Kiister  was  able  to  calculate  with  a  high 
degree  of  probability  the  molecular  weight  of  each  of  these 
substances  in  the  solid  state.  In  the  first  place  he  found 
that  with  mixtures  containing  excess  of  naphthalene  the 
ratio  of  the  square  root  of  the  concentration  of  /3-naphthol 
in  the  solid  mixture  to  the  concentration  in  the  aqueous 
solution  saturated  by  that  mixture  was  very  nearly  constant, 


SOLID  SOLUTIONS.  129 

varying  but  little  with  the  actual  composition  of  the  mixtures 
taken.  The  general  theory  of  solutions  asserts  that  when  a 
substance(here  /3-naphthol)  is  divided  between  two  immiscible 
solvents  (here  water  and  naphthalene,  or  naphtholnaph- 
thalene)  it  will  be  distributed  in  a  constant  ratio  between 
the  two  solvents,  no  matter  what  amount  of  it  be  taken, 
provided  only  the  molecular  weight  of  the  substance  is  the 
same  in  both  solvents.  In  the  case  investigated  this  does 
not  hold — the  ratio  of  the  concentrations  in  the  two  solvents 
is  not  constant ;  and  the  molecular  weight  of  /3- 
naphthol  dissolved  in  water  is  therefore  different  from  the 
molecular  weight  of  /3-naphthol  "  dissolved  "  in  naphthalene. 
The  theory  further  asserts  that  when,  as  in  the  present 
instance,  the  concentration  in  one  of  the  solvents  is  pro- 
portional to  the  square  root  of  the  concentration  in  the 
other  solvent,  the  molecule  in  the  second  solvent  must  be 
twice  as  great  as  the  molecule  in  the  first.  We  know  that 
/3-naphthol  dissolved  in  water  has  the  normal  molecular 
weight  corresponding  to  the  formula  CIOHsO  ;  in  naphthalene 
solution  it  has  consequently  the  molecular  weight  corre- 
sponding to  the  formula  (CIOH80)2. 

The  theory  of  solutions  likewise  enables  us  to  calculate 
the  molecular  weight  of  the  naphthalene  in  the  above 
experiments  from  the  diminution  of  the  solubility  of  the 
/3-naphthol  in  water  as  it  dissolves  more  and  more  naph- 
thalene. In  the  case  before  us  the  question  is  slightly  com- 
plicated by  the  existence  of  naphtholnaphthalene  molecules, 
but  Kiister  was  able  to  arrive  at  the  result  that  naphthalene 
must  have  double  the  molecular  weight  in  the  state  of  solid 
solution  that  it  has  in  the  state  of  vapour,  viz.,  (CIOH8)2. 

Another  well-investigated  case  of  solid  solutions  is  that 
offered  by  the  absorption  of  hydrogen  by  palladium. 
T roost  and  Hautefeuille,  in  order  to  obtain  information  as  to 
the  state  in  which  the  hydrogen  existed  within  the  metal, 
made  an  extensive  series  of  observations  of  the  pressure  of 
hydrogen  in  equilibrium  with  palladium  containing  different 
amounts  of  hydrogen.  They  found  that  with  compositions 
of  the  solid  up  to  one  atom  of  hydrogen  to  two  atoms  of 
palladium     the    pressure    of    hydrogen   remained   constant 

9 


i3o  SCIENCE  PROGRESS. 

at  ioo°  C,  after  which  it  increased  rapidly  as  the  pro- 
portion of  hydrogen  in  the  solid  increased.  The  analogy 
between  this  case  and  the  case  of  the  solubility  of  mixtures 
of  /3-naphthol  and  naphthalene  in  water  is  at  once  apparent. 
In  both  instances  we  have  constancy  of  pressure  (gas- 
tension)  and  solubility  (solution-tension)  within  a  certain 
range  of  composition,  and  then  rapid  variation  with  further 
change  of  composition.  The  conclusions  arrived  at  in  both 
instances  are  also  similar.  The  constant  solubility  was 
attributed  by  Klister  to  the  formation  of  a  compound 
naphtholnaphthalene — the  constant  tension  was  attributed 
by  Troost  and  Hautefeuille  to  the  formation  of  a  compound 
Pd2H,  in  which  any  excess  of  hydrogen  was  then  absorbed. 
Quite  recently,  however,  grave  doubts  have  been  thrown 
on  the  existence  of  this  compound.  A  very  careful  repetition 
and  extension  of  Troost  and  Hautefeuille's  experiments  by  C. 
Hoitsema  has  proved  that  the  constancy  of  tension  observed 
by  these  investigators  was  not  absolute  but  only  approxi- 
mate, and  that  under  slightly  varying  conditions  the 
apparent  constancy  disappeared  altogether.  It  would 
seem,  therefore,  that  no  compound  of  palladium  and  hydro- 
gen is  formed  when  the  gas  is  absorbed  by  the  solid,  the 
state  of  the  hydrogen  being  rather  one  of  simple  solution 
in  the  palladium.  A  comparison  of  the  concentrations  of 
the  hydrogen  above  the  palladium  and  of  the  hydrogen  in 
the  palladium  indicates  that  at  very  low  pressures  the 
hydrogen  in  the  metal  exists  as  molecules  only  half  as  great 
as  those  of  the  gas,  i.e.,  as  molecules  consisting  of  only  one 
atom.  At  higher  pressures  the  concentration  of  the  free 
gas  and  that  in  the  palladium  stand  in  a  nearly  constant 
ratio,  from  which  it  is  to  be  inferred  that  the  molecule  of 
hydrogen  in  the  metal,  as  well  as  the  molecule  of  gaseous 
hydrogen,  is  represented  by  the  formula  H2. 

A  problem  which  has  long  interested  chemists  is  the 
determination  of  the  nature  of  the  process  involved  in  dyeing. 
Some  contended  that  the  process  was  one  of  chemical  union  of 
the  dye  with  the  substance  of  the  fibre,  others  that  it  was 
merely  one  of  mechanical  absorption.  In  1890,  however, 
O.  N.  Witt  propounded  a  new  theory  which,  on  account  of 


SOLID  SOLUTIONS.  131 

its    plausibility,    met    with    a    ready    acceptance    in    many 
quarters. 

According  to  Witt  the  state  of  the  dye-stuff  in  the  fibre 
is  one  of  solid  solution,  and  many  analogies  were  advanced 
in  support  of  this  assertion.  For  example,  dyed  materials 
show  the  colour,  not  of  the  solid  dye-stuff,  but  of  the  dye- 
stuff  in  solution,  when  there  is  a  difference  of  colour  between 
the  two  states.  Solid  fuchsine  is  green,  its  aqueous  solutions 
are  red,  and  so  also  are  materials  dyed  with  it.  The  dye- 
stuff  rhodamine  in  the  solid  state  exhibits  no  fluorescence,  in 
solution  it  does,  and  silk  dyed  with  rhodamine  is  fluorescent 
likewise.  The  theory  of  Witt  thus  appeared  very  promising 
as  an  explanation  of  the  phenomena  of  dyeing,  but  a  closer 
investigation  has  shown  that  it  cannot  be  accepted  uncondi- 
tionally, although  some  modification  of  it  may  be  found  to 
satisfy  the  experimental  requirements.  It  has  been  proved 
in  a  considerable  number  of  instances  now  investigated 
that  the  concentrations  of  the  dye  in  the  dye-bath  and 
in  the  fibre  do  not  stand  to  each  other  in  a  relation 
of  simple  proportionality,  but  the  concentration  in  the  bath 
is  roughly  proportional  to  a  power  (usually  3  to  5)  of  the 
concentration  in  the  fibre.  Now  on  the  theory  of  solid 
solutions  this  indicates  that  the  molecule  of  the  dye  in  the 
water  is  three  to  five  times  as  great  as  the  molecule  of  the 
dye  in  the  silk  ;  but  this  cannot  be  the  case,  for  the  mole- 
cule of  the  dye-stuff  in  aqueous  solution  can  be  shown  by 
other  means  to  be  the  simplest  possible.  The  numbers 
rather  indicate  analogy  to  the  process  known  as  absorption 
from  solution.  Substances  like  animal  charcoal  and 
platinum  black  have  the  property  of  condensing  gases  in 
the  extensive  surface  they  present.  Similarly  they  can 
abstract  certain  substances  from  solution,  as  may  be  seen  in 
the  employment  of  animal  charcoal  for  the  decoloration  of 
solutions.  The  relation  between  the  concentration  in  the 
solution  and  that  in  the  charcoal  proves  to  be  of  the  same 
kind  as  is  met  with  in  dyeing,  so  that  we  are  led  to  suspect 
a  similarity  in  the  nature  of  the  two  processes.  The  so- 
called  "iodide  of  starch,"  the  blue  compound  formed  when 
starch  and  iodine  solution  are  brought  into  contact,  would 


i32  SCIENCE  PROGRESS. 

appear  to  be  a  substance  of  the  same  nature  as  a  dyed  fibre 
and  as  charcoal  saturated  with  an  acid  from  solution,  for  the 
concentrations  of  the  iodine  in  the  aqueous  solution  and  in 
the  starch  obey  approximately  the  same  law  as  in  the  other 
instances. 

We  are  therefore  forced  to  conclude  that  whatever 
success  has  attended  the  application  of  the  theory  of 
solid  solutions  to  other  processes,  the  theory  can  scarcely 
without  modification  be  accepted  as  giving  an  explanation 
of  the  process  of  dyeing. 

BIBLIOGRAPHY. 

J.  H.  VAN'T  Hoff.     Zeitschrift  fiir  physikalische  Chemie,  v.,  322 

(1890). 
A.  VAN  BlJLERT.     Ibid.,  viii.,  343  (1891). 
O.  N.  WlTT.     Fdrber-Zeitung,  i.  (1 890-91). 
C.  T.   HEYCOCK  and  F.   H.  Neville.     Journal  of  the  Chemical 

Society,  Ixi.,  888  (1892). 

E.  A.  Schneider.      Zeitschrift  fiir  physikalische  Chemie,  x.,  425 

(1893). 
A.  Ferratini  and  F.  GARELLI.     Gazzetta  chimica  italiana,  xxii., 

ii.,  245  ;  xxiii.,  i.,  442  (1893). 

F.  GARELLI.     Ibid.,  xxiii.,  ii.,  354  (1893). 

F.  GARELLI.     Zeitschrift  fiir  physikalische  Chemie,  xviii.,  51  (1895). 
F.  W.  KtJSTER.    Ibid.,  xii.,  508  (1893);   xiii.,  445  (1894)  5  xv»->  357 
(1895). 

F.  W.  KtJSTER.     Liebigs  Annalen,  cclxxxiii.,  360  (1894). 

C.    HoiTSEMA.       Zeitschrift   fiir   physikalische    Chemie,   xvii.,     1 
(1895). 

G.  C.  Schmidt.    Ibid.,  xv.,  56  (1894). 

E.  Beckmann  and  A.  Stock.     Ibid.,  xvii.,  120  (1895). 
J.  M.  VAN  BEMMELEN.     Ibid.,  xviii.,  331  (1895). 
G.  V.  GEORGEVICS.     Monatshefte  fiir  Chemie,  xv.,  705  (1894). 
G.  v.  Georgevics  and  E.  Lowy.     Ibid.,  xvi.,  345  (1895). 

James  Walker. 


THE    STELAR    THEORY;   A  HISTORY  AND  A 

CRITICISM. 

PART  I. 

IN  the  study  of  the  histological  anatomy  of  plants,  apart 
from  the  structure  of  the  individual  cell,  the  greatest 
advances  of  the  last  two  decades  have  been  made  rather  by 
the  establishment  of  new  points  of  view  than  by  the  dis- 
covery of  new  facts.  Twenty  years  ago  the  solid  founda- 
tions of  the  subject  had  been  securely  laid,  and  a  consider- 
able portion  of  the  imposing  fabric  of  histological  detail 
which  now  rests  upon  them  had  already  been  built  up. 
This  fact  is  most  clearly  brought  out  by  the  masterly 
summary  of  existing  anatomical  knowledge  published  by 
De  Bary  in  1877.  But  splendid  monument  as  it  is  of  its 
author's  unsurpassed  knowledge  of  his  subject,  there  can  be 
few  who  have  not  felt  that  the  Vergleichende  Anatomie 
is,  as  a  whole,  essentially  unreadable.  Compare  it,  in 
imagination,  with  Sachs'  Vorlesungen  or  with  Haber- 
landt's  Physiologische  Pflaiizenanatomie ,  and  we  are 
forced  to  recognise  that  De  Bary's  work  is  rather  an  ency- 
clopaedia than  a  piece  of  great  scientific  literature.  The 
cause  is  to  be  found  in  the  simple  fact  that  there  did 
not  exist  in  1877  a  philosophy  of  the  morphological  aspect  of 
the  subject  capable  of  informing  "  an  epitome  of  the  pre- 
sent knowledge  of  'the  Anatomy  of  the  Vegetative  Organs 
of  Vascular  Plants,'  "  as  the  idea  of  adaptation  informed  the 
works  of  Sachs  and  Haberlandt. 

It  is  nothing  less  than  the  establishment  of  such  a 
philosophy  that  we  now  owe  to  the  great  Frenchman,  Van 
Tieghem.  The  most  important  part  of  his  ideas  is  con- 
tained in  what  we  may  call  the  Stelar  Doctrine  of  Vascular 
Tissue,  and  it  is  with  this  that  we  shall  here  be  exclusively 
concerned. 

Although  the  foundations  of  the  stelar  theory  were  laid 
many  years  ago,  outside  France  it  has  made  its  way  very 
slowly.      In  Germany  even    now  it  is  apparently    ignored 


134  SCIENCE  PROGRESS. 

by  the  majority  of  anatomists,  notwithstanding  its  accept- 
ance by  the  most  brilliant  of  German  contemporary  in- 
vestigators. 

In  England,  though  these  ideas  have  recently  been 
made  familiar  to  the  student  by  more  than  one  of  our  lead- 
ing botanists,  their  discussion  has  still  the  interest  of  com- 
parative novelty.  And  although  the  general  idea  of  the 
stele  as  a  morphological  unit  is  simplicity  itself,  yet  the 
application  of  this  idea  is  in  some  cases  by  no  means  easy, 
so  that  not  only  does  Strasburger's  interpretation  of  certain 
facts  differ  from  Van  Tieghem's,  but  the  author  of  the 
theory  has  himself  been  led  to  modify  his  original  views  in 
an  important  manner.  The  possibility  of  such  a  difference 
in  the  interpretation  of  facts  which  are  undisputed  seems  to 
spring,  if  we  may  say  so  without  presumption,  from  a 
certain  want  of  definiteness  in  the  apprehension  of  the 
criteria  legitimate  to  their  interpretation. 

To  investigate  these  criteria  and  to  endeavour  to  as- 
certain their  relative  validity  is  one  of  the  primary  objects 
of  the  present  paper. 

We  shall  begin  with  an  account  of  the  development  of 
the  stelar  doctrine. 

HISTORY  OF   THE    STELAR    DOCTRINE.     FIRST    PHASE— 
THE  IDEA  OF   THE   CENTRAL   CYLINDER. 

In  1 8 70- 1,  Van  Tieghem  published,  in  the  Annales  des 
Sciences  Nattirelles,  a  memoir  (1)  which  was  to  have  been 
the  first  of  a  series  entitled  "  Recherches  sur  la  syme.trie 
de  structure  des  plantes  vasculaires".  This  instalment  con- 
sisted of  a  general  introduction  setting  forth  the  plan  of 
the  whole  work,  followed  by  274  pages  devoted  to  an  ex- 
tended anatomical  account  of  the  root,  in  vascular  plants. 

The  introduction  is  of  the  Greatest  interest.  The 
author  tells  us  how  he  wished  to  obtain  anatomical  defini- 
tions of  root,  stem,  and  leaf,  in  order  to  give  a  basis  to  the 
study  of  comparative  anatomy.  These  definitions  are  to 
be  framed  in  accordance  with  the  different  kinds  of  sym- 
metry exhibited  in  the  arrangement  of  the  vascular  strands 
in  the  three  organs,  to  each  of  which   a   separate  memoir 


THE  STELA R  THEORY.  135 

is  to  be  devoted.  The  results  so  obtained  are  to  be 
applied,  in  a  further  series  of  memoirs,  to  the  solution 
of  a  number  of  morphological  problems,  such  as  the  true 
nature  of  tendrils,  tubers,  spines,  phylloclades,  ovules,  etc., 
and  finally,  to  the  elucidation  of  the  laws  of  symmetry 
governing  the  structure  and  relations  of  the  ideal  colony 
that  would  be  formed  if  every  seed  germinated  in  situ. 

This  elaborate  scheme  for  "un  cercle  d'etudes  an- 
atomiques  complets  et  fermes "  enables  us  to  understand 
the  strength  and  the  weakness  of  the  author's  stelar  theory. 
The  imperative  desire  to  reduce  the  anatomy  of  vascular 
plants  to  a  perfect  system  depending  upon  simple  laws  of 
symmetry  governing  the  arrangement  of  the  vascular  tissue, 
has  been  the  means  of  giving  us  a  doctrine,  luminous  indeed, 
and  of  wide  significance,  but  scarcely  of  that  rigidly  uni- 
versal application  which  its  author  claims.  But  here  again, 
as  is  so  often  the  case  in  the  history  of  science,  the  attempt 
to  work  out  logically  the  various  implications  of  such  a 
theory,  has  been  of  the  utmost  value  in  clearing  our  ideas 
and  extending  knowledge,  not  only  by  stimulating  to  the 
discovery  of  new  facts,  but  by  forcing  us  to  examine  the 
foundation  of  our  conceptions. 

Of  Van  Tieghem's  scheme,  as  it  stood  in  1870,  how- 
ever, only  the  first  memoir,  that  on  the  root,  was  ever 
written.  The  author  demonstrates  the  fundamental  identity 
of  structure  in  the  roots  of  all  vascular  plants,  and  obtains  his 
anatomical  definition  based  on  the  symmetry  of  the  vascular 
system.  He  shows  that  the  vascular  tissue  of  a  young  root 
forms  a  central  cylinder  which  contains  near  its  periphery 
"  faisceaux  liberiens"  (phloems)  alternating  with  "faisceaux 
vasculaires"  (xylems)  united  by  "cellules  conjonctives ". 
Hence  the  vascular  system  is  symmetrical  in  relation  to  a 
line,  which  is  the  organic  axis  of  the  organ.  The  stem 
agrees  with  the  root  in  this  last  point,  but  on  the  other 
hand  has  its  "faisceaux  libero-vasculaires,"  "  reunis  directe- 
ment  par  le  parenchyme  primordial ".  Where  the  main 
root  passes  into  the  main  stem  there  occurs  a  "cessation  du 
tissu  conjonctif  special,  qui  se  trouve  remplace  par  le 
parenchyme  primitif  ".     This  sentence  is  specially  interest- 


136  SCIENCE  PROGRESS. 

ing  because  it  shows  that  when  it  was  written  Van  Tieghem 
had  no  idea  of  a  central  cylinder  in  the  stem. 

Two  years  later,  however,  in  1872,  in  describing  (2) 
the  transition  from  root  to  shoot  in  Tagetes  patiila,  he 
writes  how  the  "  membrane  protectrice "  (endodermis)  is 
continued  up  into  the  stem,  retaining  its  characteristic 
thickenings,  and  immediately  internal  to  it  the  "membrane 
rhizogene"  of  the  root  (later  named  the  pericycle)  is  also 
found  in  the  stem  still  giving  rise  to  rows  of  lateral  roots, 
one  row  arising  from  each  interval  between  two  bundles. 
Opposite  the  bundles,  however,  he  holds  that  the  "membrane 
rhizogene"  is  interrupted,  since  here  the  endodermis  abuts 
directly  on  the  group  of  fibres  capping  the  bundle,  fibres 
which  in  accordance  with  the  current  opinion  he  considered 
to  belong  to  the  phloem.  Here  then  we  have  the  first 
clear  description  of  the  continuation  of  the  central  cylinder 
of  the  root  into  the  stem,  and  the  idea  of  this  continuation 
is  the  fundamental  idea  of  the  stelar  theory.  It  is  most 
clearly  expressed  in  a  note  on  p.  112,  "  Ainsi,  et  j'insiste 
sur  ce  point,  la  tige  est,  comme  la  racine,  et  dans  toute  son 
etendue,  composee  d'un  cylindre  central  et  d'un  parenchyme 
cortical  limite  en  dehors  par  un  epiderme,  en  dedans  par 
une  membrane  protectrice  ou  endoderme  ". 

The  generality  of  this  condition  is  further  insisted  upon  : 
"  Le  caractere  sur  lequel  je  viens  d'appeler  l'attention  se 
retrouve  dans  la  tige  de  la  grande  majorite  des  plantes 
vasculaires,  mais  il  souffre  pourtant  quelques  exceptions. 
M.  Caspary  a  montre,  en  effet,  que  dans  quelques  plantes 
(Minyanthes  trifoliata,  Adoxa  moschatellina,  Bi-asema 
peltatd)  chaque  faisceau  constitutif  de  la  tige  est  indivi- 
duellement  entoure  par  une  membrane  protectrice  a  cellules 
plissees  ('  Bemerkungen  liber  die  Schutzscheide,'  in  Pring- 
scheims  Jahrbucher,  1865-66,  iv.,  p.  10 1).  J'ai  retrouve  le 
meme  fait  sur  quelques  autres  plantes,  notamment  sur 
r Hydrocleis  Humboldtii.  Dans  ce  cas,  il  n'y  a  pas  non 
plus  de  membrane  rhizogene  dans  les  entrenceuds  de  la 
tige,  et  il  n'existe  aucune  solution  de  continuity  aucune 
distinction  reelle  entre  le  parenchyme  cortical  et  la  moelle  ' 
(p.    113).     This   paragraph  shows  clearly   that   thus    early 


THE  STELA R  THEORY.  137 

Van    Tieghem    had    recognised    the    condition    which    he 
afterwards  described  as  "  astely  ". 

The  "membrane  rhizogene,"  now  considered,  under  the 
name  of  pericycle,  as  forming  merely  the  external  layer  of 
the  conjunctive  tissue  of  the  cylinder,  was  at  that  time 
treated  as  a  region  external  to,  and  distinct  from,  the  rest 
of  the  parenchyma,  to  which  the  name  "  conjonctif "  was 
given.  But  the  clear  recognition  of  the  existence  of  an 
individualised  stem  cylinder,  forming  a  direct  continuation, 
tissue  for  tissue  of  that  of  the  root,  was  the  first  and  funda- 
mental step  in  the  evolution  of  the  stelar  idea. 

Little  progress  was  made  during  the  next  ten  years  in 
the  development  of  this  conception. 

Falkenberg  (3),  in  1876,  showed  that  the  "  Aussen- 
scheide "  in  monocotyledonous  rhizomes  corresponds  with 
the  "  pericambium "  in  roots,  both  in  position  and  role ; 
and  Mangin  (4)  in  1882  entirely  confirmed  his  results  and 
showed  that  not  only  adventitious  roots  but  also  the 
"  reseau  radicifere "  arises  from  this  layer,  which  he  calls 
the  "  couche  dictyogene  ". 

In  1882  Van  Tieghem  published  a  short  paper  (5)  in 
which,  a  propos  of  the  Cucurbitacese,  he  gives  conclusive 
reasons,  based  upon  grounds  of  comparative  anatomy,  for 
regarding  the  fibres  in  the  stem,  hitherto  called  primary 
"bast  fibres,"  as  really  belonging  to  the  "membrane 
rhizogene  ".  With  these  extended  limits,  this  layer  forms  a 
complete  investment  of  the  stem  cylinder,  just  as  the  peri- 
cambium does  of  the  root  cylinder.  Since  the  one  layer  is 
the  direct  continuation  of  the  other,  and  the  two  correspond 
very  largely  in  function  as  well  as  in  position,  it  is  clearly 
desirable  that  they  should  have  a  common  name.  For  this 
purpose  Van  Tieghem  introduced  the  word  pericycle,  which 
was  to  supersede  the  various  terms  "pericambium," 
"  Aussenscheide,"  "membrane  rhizogene,"  "couche  dictyo- 
gene," etc.,  applied  by  various  writers  to  the  same  layer  in 
various  plants  and  parts  of  plants,  according  to  its  various 
histological  characters  and  functions.  The  importance  of 
this  introduction  of  the  conception  of  the  pericycle  was  of 
course  very  great,  since  it  fixes  more  accurately  the  external 


138  SCIENCE  PROGRESS. 

limit  of  the  cylinder,  and  thus  brings  into  greater  promi- 
nence the  idea,  already  clearly  stated  in  1872,  of  an  indi- 
vidualised stem  cylinder  in  direct  continuity  with  that  of 
the  root. 

The  term  has  eventually,  though  very  slowly,  found 
its  way  into  general  use. 

In  1884  Morot,  a  pupil  of  Van  Tieghem,  published  the 
results  of  a  research  (6)  devoted  to  a  comparative  investiga- 
tion of  the  pericycle  in  both  root  and  shoot. 

The  publication  of  Morot's  paper  brings  to  an  end  what 
we  may  call  the  first  phase  in  the  development  of  the  stelar 
idea. 

SECOND  PHASE— POLYSTELY  AND  ASTELY. 

The  second  phase  was  inaugurated  in  an  investigation  (70) 
by  Van  Tieghem  and  his  pupil  Douliot,  of  the  anatomy  of  the 
stem  of  various  species  belonging  to  the  genus  Primula.  Their 
observations  were  carried  out  on  a  number  of  new  species  from 
the  East,  as  well  as  on  many  old  species,  making  together  a 
total  of  114.  They  resulted  [yd)  in  a  division  of  the  aggre- 
gate genus  Primula  L.,  into  two  segregates,  Primula  Tourn. 
and  Auricula  Tourn.,  as  had  been  already  done  by  Tourne- 
fort,  but  now  based  on  a  fundamental  difference  in  the 
structure  of  the  stem  of  the  two  segregate  genera.  While 
the  stem  of  the  species  belonging  to  Primula  possesses 
a  single  normal  central  cylinder  in  its  whole  extent,  the 
narrow  cylinder  of  the  hypocotyl  of  an  Auricula,  instead 
of  dilating  in  the  ordinary  way  above  the  level  of  the  coty- 
ledons, gives  rise  by  successive  bifurcations  to  two  or  more 
vascular  strands,  each  surrounded  by  an  endodermis  and 
possessing"  the  structure  of  the  single  hypocotyledonary 
cylinder.  In  the  genus  Gunnera  {Haloragece)  a  similar 
state  of  things  obtains.  These  facts  were,  in  the  main, 
already  known,  having  been  investigated  by  Vaupell, 
Kamienski  and  Reinke.  The  opinion  of  these  authors 
was,  however,  that  the  separate  vascular  strands  were  vas- 
cular bundles  of  the  "  concentric "  type  with  peripheral 
phloem,  comparable  for  instance  to  those  found  in  the 
cortex  of   certain    Mclastoniace<z ;   and   this   was   the    view 


THE  STELA R  THEORY.  139 

taken  by  De  Bary  in  his  classical  Vergleichende  Anatotnie. 
The  numerous  vascular  strands  in  the  rhizomes  of  most 
Leptosporangiate  Ferns  were  regarded  by  De  Bary  in  the 
same  light. 

But  Van  Tieghem,  having,  as  we  have  seen,  come 
to  regard  the  central  cylinder  rather  than  the  bundle  as 
the  morphological  unit  of  vascular  tissue  in  both  root  and 
shoot,  was  now  led  to  the  conclusion  that  in  Auricula, 
Gunnera  and  the  majority  of  Ferns  1  we  have  really  to 
deal  with  a  splitting-  of  the  single  cylinder  of  the  hypocotyl, 
as  we  trace  it  upwards,  by  successive  bifurcations,  into  a 
number  of  such  cylinders  (jc  and  8).  Van  Tieghem 
and  Douliot  proposed  to  call  such  a  cylinder  a  stele  (Greek 
<7r/;X»7,  a  column).  A  root  or  a  stem  containing  one  such 
stele  would  be  monostelic,  if  it  contained  more  than  one 
polystelic.  A  third  case  was  distinguished.  If  the  cylinder 
of  the  hypocotyl  breaks  up,  as  it  is  traced  upwards,  into 
its  component  bundles,  each  of  which  is  surrounded  by  a 
special  endodermis,  the  cylinder,  according  to  our  authors, 
no  longer  exists  ;  the  stem  is  astelic.  This  case,  already 
described  in  1872,  obtains  in  the  stems  of  various  Ranun- 
culacece,  in  Nymphceacece,  in  Hydrocleis,  in  some  species  of 
Equisetum,  etc.,  as  well  as  in  the  majority  of  petioles  and  in 
blades  of  all  leaves. 

Cases  of  Polystely  fall  into  two  groups.  First,  where 
on  a  transverse  section  the  various  steles  are  seen  to  be 
completely  separate,  we  have  a  state  of  dialystely.  Secondly, 
where  the  steles  are  united  laterally,  so  as  to  form  a  more  or 
less  complete  ring  in  transverse  section,  enclosing  a  more  or 
less  isolated  portion  of  extra-stelar  tissue,  which  occupies  the 
centre  of  the  ring,  we  have  a  state  of  gamostely.  These 
two  conditions  are  not  to  be  sharply  separated,  since  the 
steles  of  all  polystelic  stems  show  more  or  less  frequent 
lateral  unions,  and  the  gamostelic  condition  is  simply  a 
case  where  these  unions  are  very  frequent  and  persistent. 

1  Leclerc  du  Sablon  in  1890  (9)  worked  out  the  connections,  in 
several  Ferns,  of  the  single  hypocotyledonary  cylinder  with  the  cylinders 
of  stem. 


140  SCIENCE  PROGRESS. 

We  may  tabulate  the  results  thus  obtained  as  follows: — 

Monostely. — A  single  central  cylinder.  All  roots  and 
hypocotyls,  nearly  all  Phanerogamic  stems,  and  stems  of 
many  Vascular  Cryptogams. 

Polystely. — More  than  one  cylinder.  Stems  of  most 
ferns,  most  species  of  Selaginella,  and  among  Phanerogams 
of  Auricula  and  Gunner  a} 

(a)  Dialystely.— Steles  separate  for  most  of  their 
course.  Most  Ferns  Selaginella  and.  Auricula  ursi,  etc. 
Gunnera. 

(6)  Gamostely. — Steles  united  laterally  for  most  of  their 
course.  Marsilia,  Pilularia,  Pteris  aurita,  etc.  Auri- 
cula japonica,  etc. 

Astely. — No  cylinder.  Leaf  blades,  most  petioles, 
stems  of  some  species  of  Equisetum  and  Ranunculus^ 
stems  of  Hydrocleis,  Ophioglossum,  Limnanthonum,  Nym- 
phceacece,  etc.  (yc). 

The  publication,  in  1890-91,  of  the  second  edition  of 
Van  Tieghem's  Trait e"  de  Botanique  (10),  which  contains  a 
full  exposition  of  the  stelar  doctrine  on  the  lines  indicated, 
may  be  said  to  mark  the  close  of  the  second  phase  in  the 
development  of  the  theory. 

THIRD  PHASE— EXTENSIONS  AND  MODIFICATIONS. 

The  third  phase,  from  that  date  to  the  present  time,  has 
been  occupied  by  various  developments  and  modifications  of 
the  doctrine  on  the  part  of  the  author  and  his  pupils,  and  has 
been  marked  by  considerable  criticism,  mainly  of  these 
newer  developments. 

The  first  line  of  research  that  calls  for  notice  is  a  re- 
investigation of  the  conjunctive  tissue  of  the  typical  central 
cylinder  of  the  flowering  plant.     This  has  led  Flot  (11)  to 

1  In  a  paper  recently  communicated  to  the  Linnean  Society,  Mr.  B. 
G.  Cormack  describes  cases  of  polystely  met  with  in  the  adventitious  roots 
of  three  genera  of  Palms,  viz.,  Areca,  Cocos  and  Verschaffeltia.  It  appears 
that  the  single  stele  of  the  root  splits,  as  it  is  traced  downwards,  into  a  ring 
of  separate  steles.  Later  on  these  steles  again  pass  over  into  a  single 
cylinder.  This  seems  to  be  an  important  modification  of  Polystely  as 
described  by  Van  Tieghem  and  Douliot,  and  Leclerc  du  Sablon. 


THE  STELA R  THEORY.  141 

add  a  new  region  to  those  already  distinguished.  He 
finds  a  zone  situated  at  the  periphery  of  the  pith,  i.e.,  just 
internal  to  the  ring  of  bundles,  corresponding  exactly  to 
the  pericycle  external  to  the  ring,  as  well  characterised 
histologically  as  the  pericycle  itself,  and  indeed  resembling 
the  latter  very  closely  in  structure  and  role.  This  zone, 
the  perimedullary  zone,  is  according  to  Flot  (and  his 
figures  entirely  support  this)  separate  in  development  from 
the  pith  proper,  or  internal  conjunctive,  and  belongs  rather 
to  the  hollow  cylinder  of  tissue  (the  "thickening  ring  "  of  the 
older  German  anatomists)  giving  rise  to  the  bundles  and 
the  conjunctive  immediately  surrounding  them  {external 
conjunctive).  It  is  impossible  sharply  to  separate  the  peri- 
medullary zone  on  the  one  side,  just  as  Morot  found  it 
impossible  to  separate  the  pericycle  on  the  other,  from  the 
ray  tissue,  and  we  should  rather  regard  the  contrast  of 
the  pith  with  the  external  conjunctive  tissue,  as  of  greater 
importance  than  the  division  of  the  latter  into  pericycle, 
rays  and  perimedullary  zone,  which  are  in  the  main 
topographical  regions  marked  out  by  the  limits  of  the 
bundles.  In  many  adult  stems  it  is  however  impossible  to 
fix  the  limits  of  external  and  internal  conjunctive,  just  as 
it  is  often  impossible  to  fix  the  limits  between  external  con- 
junctive and  cortex.  Flot  is  of  opinion  that  this  is  owing 
to  a  growth  in  breadth  of  the  cells  of  the  external  conjunc- 
tive continued  longer  than  in  the  pith,  the  whole  of  the  tissue 
of  the  cylinder  thus  becoming  approximated  in  size  and 
shape.  This  same  cause,  together  with  a  masking  of  the 
endodermal  thickenings  (in  cases  where  these  are  originally 
present)  by  a  general  thickening  of  the  walls  of  all  the 
parenchyma  cells  may  very  conceivably  account  for  the 
frequent  absence  of  the  obvious  limit  between  cortex  and 
cylinder,  though  we  are  not  aware  that  such  an  occurrence 
has  been  either  established  or  suggested.1  Further  in- 
vestigation on  this  point,  as  well  as  on  the  separation  of 
the  regions    in   root   cylinders  with  a  well-developed  con- 

XI  now  find  that  Sanio  (24,  pp.  371-2)  states  that  this  is  practically 
what  occurs  in  the  stem  of  Ranunculus  acris. 


i42  SCIENCE  PROGRESS. 

junctive  system,   is  much   needed   to  complete   our   know- 
ledge of  these  matters. 

An  important  modification  of  the  theory  of  steles  has 
been  made  by  Van  Tieghem  himself  in  extending  the  use 
of  the  term  astely  so  as  to  make  it  include  the  state  of 
things  obtaining  in  the  stems  of  all  species  of  Equisetum 
(12),  and  of  0 p  hio gloss  ace  ce  (13). 

Let  us  take  first  the  case  of  Equisetum.  Well- 
marked  endodermes  are  found  in  the  stems  of  all  species, 
but  their  disposition,  which  was  fully  worked  out  many 
years  ago  by  Pfitzer,  is  very  various,  not  only  in  different 
species,  but  in  different  parts  of  the  stem  of  the  same 
species.  There  are  three  types  of  arrangement.  In  the 
first  each  vascular  bundle  is  surrounded  by  a  special  endo- 
dermis  ;  in  the  second  the  ring  of  bundles  is  bordered  within 
and  without  by  a  general  endodermis  ;  and  in  the  third 
the  outer  endodermis  alone  is  present.  In  the  second 
edition  of  the  Traite  Van  Tieghem  assigned  the  first 
two  conditions  to  the  astelic,  the  third  to  the  monostelic 
type,  but  in  a  paper  (12)  published  in  the  same  year  (1890) 
he  calls  attention  to  the  fact,  discovered  by  Pfitzer,  that 
all  the  species  possess,  at  their  nodes,  the  first  or  second  of 
the  arrangements  in  question.  He  therefore  concludes 
that  all  belong  really  to  the  astelic  type,  and  that  where, 
for  instance,  the  second  type,  just  above  a  node,  passes 
back  into  the  third,  we  have  simply  a  case  of  the  dis- 
appearance of  the  special  characters  of  the  inner  endo- 
dermis, which  must  still  be  supposed  to  exist.  The  "  mono- 
stely"  is  only  apparent,  and  the  tissue  bordering  the 
central  canal  of  the  stem,  internal  to  the  inner  (theo- 
retical) "endodermis,"  is  not  in  reality  pith,  but  rather 
"  inner  cortex"  (extra-stelar  tissue).  The  first  of  the  three 
arrangements  is  to  be  called  dialydesmic,  since  each  bundle 
with  its  sheath  of  conjunctive  is  separate  ;  the  second  and 
third  gamodesmic,  since  the  conjunctive  tissue  surrounding 
the  bundles  is  in  lateral  confluence. 

Turning  now  to  the  Ophioglossacece  we  have  a  similar 
argument  (13).  The  stem  of  Ophioglossum  vulgahtm, 
below  the  level  of  the  first  leaf,  is  monostelic,  but  above  the 


THE  STELA R  THEORY.  143 

first  leaf  contains  five  separate  bundles  each  with  a  separate, 
though  feebly  suberised,  endodermis.  Hence  it  was 
treated  by  Van  Tieghem,  in  the  Traits,  as  astelic.  In 
Botrychium  Lunaria,  whose  stem  is  also  monostelic  at  the 
base,  the  endodermis,  after  the  departure  of  the  first  leaf 
trace,  does  not  close  round  each  separate  bundle  but 
becomes  as  it  were  invaginated  into  the  cylinder,  so  that 
the  vascular  tissue  forms  on  transverse  section  a  horse- 
shoe bounded  by  the  endodermis.  The  free  edges  of  the 
horseshoe  meet,  as  we  pass  up  the  stem,  and  the  inner 
portion  of  the  endodermis  becomes  entirely  separated  from 
the  outer,  so  that  we  have  an  equivalent  of  the  second  or 
gamodesmic  condition  found  in  the  stems  of  Eqtiiseta. 
Higher  up  the  inner  endodermis  loses  its  thickenings,  just 
as  in  some  Equiseta,  and  this  gives  us  an  apparently 
monostelic  condition.  In  accordance  with  his  revised 
view,  Van  Tieghem  considers  that  OpJiioglossum  has  an 
astelic-dialydesmic  stem,  while  those  of  Botrychium  and 
Helminthostachys  are  astelic-gamodesmic. 

THE  STATUS  OF   THE  STELE  CRITICISM. 

It  will  be  most  convenient  to  introduce  here  a  critical 
investigation  of  the  stelar  theory  as  thus  modified  by  its 
author,  and  so  far  as  it  depends  upon  the  morphological 
interpretation  of  the  arrangement  and  relations  of  vascular 
tissue  in  the  adult  organs  of  vascular  plants  ;  deferring  for 
the  present  a  consideration  of  the  developmental  facts 
bearing  upon  the  theory. 

There  is  no  need  to  discuss  at  any  length  the  funda- 
mental conception  of  the  stele  arrived  at  in  the  period  which 
we  have  called  the  first  phase  of  development  of  the  idea. 
It  depends  upon  the  tracing  into  the  stem  of  the  root 
cylinder,  and  upon  the  demonstration  that  its  characters  as 
a  cylinder  are  maintained  in  the  latter.  This  demonstration, 
begun,  as  we  have  seen,  in  1872,  eventually  led  to  the 
explicit  recognition  of  the  fact  that  the  system  of  bundles 
forming  the  central  cylinder  possesses  morphological  charac- 
ters much  more  constant  than  those  of  the  vascular  bundle, 


144  SCIENCE  PROGRESS. 

and  is  hence  more  worthy  to  be  taken  as  the  morphological 
unit  of  vascular  tissue.  It  is  indeed  impossible  to  give  a 
morphological  definition  of  a  vascular  bundle  at  all.  "  From 
the  very  first  those  bundles  which  consist  essentially  of 
definitely  arranged  groups  of  tracheae  and  sieve  tubes  .  .  . 
have  been  called  vascular  bundles"  (14,  p.  232,  Eng.  ed.). 
But  thus  defined,  a  "vascular  bundle"  has  no  constant 
histological  characters  beyond  the  fact  of  containing  both 
xylem  and  phloem.  According  to  the  arrangement  of  these, 
bundles  have  been  classified  as  radial,  concentric,  collateral, 
etc.  Such  an  arrangement  brings  together  vascular  strands 
of  very  different  orders  of  complexity.  In  the  first  place 
it  associates  the  axial  cylinder  ("radial  bundle")  of  a  root, 
possessing  a  number  of  quite  distinct  xylem  and  phloem 
strands,  with  the  "collateral  bundle"  of  a  Phanerogamic 
stem,  formed  of  a  single  strand  of  xylem  and  phloem  in  close 
association,  the  latter  being  continuous  moreover  with  a 
portion  only  of  the  former.  Again  it  associates  even  more 
closely  under  the  term  "  concentric  bundle  "  the  vascular 
strands  found  in  the  stem  of  Auricula,  Gunnera  and  Ferns 
with  those  of  quite  different  structure  found  in  the  pith  and 
cortex  of  Melastomacecz,  etc. 

Such  a  classification  is  clearly,  from  a  morphological  point 
of  view,  quite  artificial.  But  if  we  extend  the  use  of  the  term 
bundle,  as  is  often  done,  so  as  to  include  strands  of  tracheae 
alone,  and  of  sieve  tubes  alone,  we  can  retain  it  as  a  con- 
venient word  without  morphological  connotation,  and 
applicable  to  any  strand  of  tissue  belonging  to  the  vascular 
system.  And  we  may  then  qualify  the  word  by  any  adjec- 
tive we  choose  without  morphological  implication.  Thus  we 
may  speak  of  the  composite  radial  bundle  of  the  root  as 
composed  of  separate  xylem  bundles  and  phloem  bundles 
alternating  at  its  periphery  ;  of  the  concentric  bundle  of  the 
stem  of  an  aquatic  plant  as  sometimes  composed  of  separate 
collateral  bundles,  in  other  cases  consisting  simply  of  a  con- 
tinuous cylinder  of  phloem  surrounding  a  central  strand  of 
xylem  ;  of  the  concentric  bundle  of  a  fern  petiole  gradually 
passing  to  the  collateral  type  as  we  trace  it  into  the  lamina, 
and  so  on.      Meanwhile  the  study  of  the  homologies  of  the 


THE  STELA R  THEORY.  145 

various  strands   is  quite  a  distinct   matter,  and   requires   a 
distinct  terminology. 

THE  BOUNDARY  OF  THE  STELE. 

The  acceptance  of  the  central  cylinder  in  the  "  mono- 
stelic  "  stem  as  a  region  of  the  first  morphological  rank  is 
now  very  general.  The  only  criticism  which  we  have  to 
consider  is  that  which  calls  attention  to  the  frequent  want 
of  definiteness  about  its  external  limit,  and  is  inclined  on 
this  ground  to  question  its  individuality.  This  want  of 
definiteness  arises  from  the  absence,  in  many  adult  stems, 
of  the  special  characters  of  the  endodermis  (innermost 
layer  of  the  cortex),  often  combined  with  an  identity  in 
size,  shape  and  characters  of  cell-membrane  between 
the  cells  of  the  cortex  and  those  of  the  conjunctive.  Such 
a  state  of  things  obtains,  to  take  a  single  instance,  in  the 
stem  of  Ranunculus  repens.  A  transverse  section  of  such 
a  stem  shows  the  separate  bundles  imbedded  in  a  homo- 
geneous ground  tissue,  and  to  speak  of  a  well-marked  central 
cylinder  is  to  speak  of  that  which  does  not,  in  fact,  exist. 

Now  this,  as  it  stands,  is  a  perfectly  legitimate  criticism, 

and  its  force   as   against  the  general  validity  of  the   stelar 

idea  depends  simply  upon  the  greater  or  less  generality  of 

the  condition  described.     Van  Tieghem  (10,  p.  752)  states 

that  when,  after  the  formation  of  the  endodermis,  the  stem 

undergoes    considerable    intercalary   growth,   the   folds    on 

the  radial  walls  of  the  endodermal  cells  become  stretched  out 

so  that  they  become  difficult  or  impossible  to  see.      In  other 

cases  no  suberisation  of  the  radial  walls  occurs,  and  then, 

unless  the  endodermal  cells  are  distinguished  by  possessing 

starch,  it  is  admitted  that  the  limit  of  the  cylinder  is  difficult 

to  determine,  but  says  Van  Tieghem  {Joe.  eit.) :  "  il  reste  la 

forme  differente  des  cellules  ".     This,  however,  as  has  been 

said,  is  by  no  means   always   obvious.      A  possible  cause  of 

such  a  condition,  assuming  the  limits  of  the  young  cylinder 

to    be    well    defined,    has    already    been    suggested,    but 

new  investigations   are   necessary   to   determine  the  point. 

If,  for  the  sake  of  argument,  we  make  the  opposite  assump- 

10 


146  SCIENCE  PROGRESS. 

tion,  that  the  vascular  bundles  are  sometimes  differentiated 
in  the  middle  of  a  homogeneous  ground  tissue,  no  trace 
of  a  special  endodermis  or  pericycle  being  visible  at  any 
time,  we  could  not  predicate  the  existence,  in  such  cases, 
of  a  central  cylinder  in  the  stem.  And  further,  if  such 
a  condition  obtained  in  the  majority  of  instances  (certainly 
an  unlikely  supposition)  we  should  not,  of  course,  be 
justified  in  predicating  the  general  existence  in  the  stem 
of  a  central  cylinder,  and  this  would  necessitate  such  a 
radical  modification  in  the  generalised  statement  of  the 
facts,  that  the  stelar  idea  would  lose  the  greater  part  of 
its  significance.  We  shall  have  to  recur  to  a  discussion 
of  the  limit  of  the  cylinder,  but  these  simple  considera- 
tions are  insisted  upon  here,  because  they  are  apparently 
lost  sight  of  in  much  of  the  current  writing  of  Van  Tieg- 
hem's  adherents.  It  seems  to  be  implicitly  assumed  that  if 
a  good  anatomical  distinction  can  be  made  in  a  certain 
number  of  cases,  it  is  permissible  to  generalise  the  distinc- 
tion and  erect  it  into  a  morphological  doctrine.  The 
existence  of  those  cases  to  which  the  doctrine  does  not 
apply  is  either  ignored,  or  the  distinction  is  said  to  be 
"  theoretical  ".  There  is  of  course  no  such  thing  as  a  true 
"theoretical"  distinction  which  is  not  also  actual.  The 
fallacy  arises  from  a  tendency  to  regard  all  morphological 
doctrine  as  of  absolute  value,  whereas  its  value  is  never 
anything  but  relative.  What  we  have  to  decide  in  any 
given  case  is  the  amount  of  this  relative  value,  and  whether 
that  amount  is  sufficient  to  make  the  doctrine  express  a 
general  truth  so  far  as  the  objects  under  consideration  are 
concerned. 

The  foregoing  reflections  lead  us  naturally  to  consider 
those  cases  which  Van  Tieghem  himself  excepts  from  the 
application  of  the  stelar  doctrine,  namely,  the  cases  of 
"astely".  Already  in  the  earliest  paper  containing  the 
germ  of  the  stelar  idea  we  find  certain  cases  not  covered 
by  the  general  statement  of  the  existence  of  a  cylinder  in 
the  stem.  In  1886  these  cases  together  with  other  similar 
ones  were  called  astelic,  and  more  recently  still  the  concep- 
tion has  been  further  elaborated. 


THE  STELA R  THEORY.  147 

The  conception  is  governed  throughout  by  the  idea  of 
the   endodermis  as  a  definite  morphological  layer,  always 
separating"  stelar    from    extra-stelar   tissue.       And   the  en- 
dodermis  is    to   be    recognised  by  the    suberised    thicken- 
ings on  its  radial  walls.      It  is  simply  by  the  disposition  of 
layers  of  cells  so   thickened  that  we  are   supposed   to  be 
able    to    distinguish    the    various   arrangements    described. 
It  is  easy  to  show  that  this  criterion  is  quite  illegitimate. 
The  term  endodermis  is  defined  by  Van  Tieghem  as  the 
innermost  layer  of  the  cortex  which  "  offre  frequemment  " 
the    special   character   in    question   (10,    pp.    738-9).      Not 
only,    however,    do    cell    layers    with    the    same    character 
occur  in  quite  other  situations  {e.g.,  in  the  middle  of  many 
periderms),  but  the  innermost  layer  of  the  cortex  certainly 
does    not    always    possess    it.     So    that    these  thickenings 
cannot    be   used    to  mark   a    layer   of  invariable  morpho- 
logical value.     And  even  in  Equisetum,  Van  Tieghem  does 
not  keep    to   his   own   criterion.      For  when    the    "  astelic 
gamodesmic "    passes    to    the   apparently    monostelic    con- 
dition   we    are    told    that    the    inner    endodermis    is    still 
present    though    its    special    characters    have    disappeared. 
But,  we  may  well  ask,    if  such  great    importance  is  to  be 
attached   to  these   special    characters  as    to   justify    us  in 
founding  new  types  of  structure  simply  upon  the  disposition 
of  the  layers  exhibiting  them,  why  should  we  be  suddenly 
asked  to  recognise  as  equivalent    a  layer  which  does  not 
exhibit  them  ?     The  criterion  becomes  completely  chimeri- 
cal. 

Strasburger  (15)  has  pointed  out  that  an  endodermoid 
layer  is  an  air-tight  barrier  which  does  not  prevent  the 
passage  of  water  through  its  cells.  Such  a  layer  is  found 
in  a  position  to  shut  off  the  water-conducting  system  of  a 
plant  from  its  air-containing  lacunar  system,  but  this  posi- 
tion may  vary  within  the  same  genus  [Ranunculus, 
Equisetum),  and  has  no  necessary  connection  with  any 
morphological  region.  As  a  matter  of  fact  it  is  most  often 
formed  from  the  inner  layer  of  the  cortex,  but  may  be 
developed  from  conjunctive  tissue,  or  even  (leaf  of  Isoetes) 
from    intra-fascicular   parenchyma.       Since    the    innermost 


148  SCIENCE  PROGRESS. 

layer  of  the  cortex  does  not  always  possess  the  special 
thickenings  which  give  it  the  right  to  be  called  a 
"  membrane,"  Strasburger  objects  to  Van  Tieghem's  re- 
definition of  the  word  endodermis,  and  proposes  to  sub- 
stitute the  term  Phloeoterma,  to  be  applied  to  the  inner 
layer  of  the  cortex,  i.e.,  to  be  used  in  the  strictly  morpho- 
logical sense,  whether  this  inner  layer  has  special  characters 
or  not,  and  to  reserve  the  term  endodermis  in  accordance 
with  its  original  sense  for  any  sheath  or  membrane  com- 
posed of  cells  with  suberised  radial  walls  or  other  dis- 
tinctive thickenings,  without  reference  to  its  position. 
This  revised  terminology  certainly  helps  us  to  get  rid 
of  the  confusion  of  thought  manifested  in  Van  Tieg- 
hem's use  of  the  word  endodermis.  Strasburger  concludes 
that  as  all  species  of  Equisetum  agree  in  possessing  a  ring 
of  simple  collateral  bundles,  they  should  all  be  considered 
monostelic,  whether  the  phloeoterma  be  developed  as  a 
general  endodermis,  or  each  bundle  possess  a  special 
endodermis,  the  phloeoterma  having  no  characters  by  which 
it  can  be  distinguished.  The  same  considerations  would 
apply  to  the  genus  Ranunculus  and  the  other  cases  of 
"astely  ".  While  we  must  fully  admit  the  general  force  of 
his  argument  on  the  ground  of  comparative  anatomy,  it  is 
difficult  to  agree  with  the  following  sentence  :  "  Die 
Grenze  der  Rinde  gegen  den  Centralcylinder  ist  dort  wo 
sie  sich  nicht  besonders  als  Endodermis  oder  Starkescheide 
markirt,  nur  theoretisch  zu  ziehen,  dieselbe  ist  aber  flir  alle 
Falle  festzuhalten ':  (15,  p.  484).  How  is  one  to  "hold 
fast "  a  limit  which  one  cannot  distinguish  ?  We  can  only 
refer  to  the  remarks  which  have  been  already  made  upon 
this  subject,  but  we  shall  briefly  recur  to  the  subject  in 
considering  the  development  of  the  stele. 

Leaves  furnish  us  with  excellent  examples  of  the  frequent 
impossibility  of  separating  stelar  from  extra-stelar  tissue. 
Putting  aside  those  cases  in  which  one  or  more  steles 
from  the  polystelic  stem  directly  enter  the  petiole 
[Gunncra,  Ferns),  we  have  to  consider  the  ordinary 
case  in  a  flowering  plant,  where  we  have  one  or  more 
bundles  leaving  the  cylinder  and  passing  into  the  petiole. 


THE  STELA R  THEORY.  149 

These  bundles  are  accompanied  by  a  certain  amount  of 
closely  associated  parenchyma  belonging  to  the  external 
conjunctive  of  Flot,  a  tissue  which  in  the  leaf  Van  Tieghem 
now  calls  peridesm  (16).  The  bundles  are  sometimes 
arranged  in  a  ring,  and  the  whole  may  be,  though  com- 
paratively rarely,  surrounded  by  an  endodermis.  The 
petiole  is  then,  according  to  Van  Tieghem  (10,  p.  842), 
monostelic.  In  the  commoner  case  where  each  bundle  has 
an  endodermis  of  its  own  the  petiole  is  astelic. 

Strasburger  prefers  the  term  schizostelic  (15),  since  the 
stelar  tissue  of  the  petiole  represents  a  separated  portion  or 
portions  of  that  of  the  stem.  To  such  a  portion  he  gives  the 
name  schizostele  or  schistostele  \  at  the  same  time  denying  the 
existence  of  monostelic  petioles  in  Phanerogams  on  the 
ground  that  the  apparent  pith  of  the  petiole  is  continuous 
with  the  cortex,  and  not  with  the  pith,  of  the  stem.  This 
last  contention  brings  forward  a  difficult  position.  Is  it  de- 
sirable to  introduce  the  question  of  continuity  at  all  ?  If  we 
have  in  the  petiole  a  structure  apparently  identical  with  that 
which  we  have  agreed  to  call  monostelic  in  the  stem,  should 
we  be  satisfied  to  call  it  monostelic  here  also,  without  con- 
sidering the  connections  of  its  parts  with  those  of  the  stem  ? 
The  strength  of  Strasburger's  position  lies  in  the  fact  that 
the  continuity,  region  for  region,  of  the  cylinder  of  root 
and  stem  is  really  the  basis  of  the  stelar  idea.  The  origin 
of  the  difficulty  is  to  be  found  in  the  tendency  of  a  petiole, 
where  it  is  subject  to  the  same  conditions  as  a  stem,  to 
assume  the  characters  of  a  stem,  and  among  them  the 
arrangement  of  its  vascular  tissue  according  to  a  radially 
symmetrical  type.  We  might,  perhaps,  fitly  call  such  a 
structure  a  pseudostele. 

The  mesophyll  of  the  leaf  (corresponding  with  the  cortex 
of  the  stem)  which  surrounds  the  smaller  vascular  bundles, 
often  has  its  innermost  layer  or  phloeoterma,  which  abuts 

1Van  Tieghem  has  since  (17,  p.  285)  used  the  word  meristele  for 
Strasburger's  "  schizostele,"  and  applied  the  latter  term  to  the  portion  of 
stelar  tissue  enclosed  by  each  special  endodermis  in  an  "astelic"  stem. 
This  seems  an  unwarrantable  diversion  of  the  meaning  of  Strasburger's 
term. 


i5o  SCIENCE  PROGRESS. 

immediately  upon  the  peridesm  of  the  bundle,  specially 
characterised.  The  cells  of  the  phloeoterma  are  often  de- 
prived of  chlorophyll,  or  this  is  confined  to  the  side  walls, 
and  these  walls  may  also  be  suberised.  It  is,  however,  a 
rare  case  for  such  layers  to  be  united  in  a  continuous 
system  with  the  phloeoterma  of  the  stem,  and  thus  to  shut 
off  completely,  by  means  of  a  continuous  membrane,  the 
entire  stelar  system  of  the  plant  from  its  cortical  tissue. 
This  state  of  things  obtains,  however,  in  Pinus  and  some 
dicotyledonous  genera,  e.g.,  Galium.  In  most  dicotyledo- 
nous petioles  endodermoid  layers,  if  distinguishable  at  all, 
are  often  incomplete  and  not  necessarily  formed  from  the 
phloeoterma.  A  closed  sheath  to  the  bundles  is,  however, 
often  formed  in  Angiosperm  petioles  by  thickened  peri- 
desmic  (stelar)  tissue,  such  a  sheath  being  called  by  Stras- 
burger  a  stelolemma  (15).  The  ensemble  of  the  phenomena 
shows  us,  clearly  enough,  that  the  endodermis,  in  its  original 
sense,  cannot  be  taken  here,  any  more  than  in  the  stem, 
as  a  layer  of  constant  morphological  value.  The  phloeo- 
terma may  be  distinguishable  by  endodermal  or  other  char- 
acters, but  on  the  other  hand,  it  may  not. 

The  main  fact  in  regard  to  the  vascular  system  of  the 
leaf  is  one  which  was  pointed  out  by  Van  Tieghem  in  1870. 
The  system  is  bilaterally  symmetrical  in  relation  to  the 
plane  including  the  organic  axes  of  both  leaf  and  stem, 
and  not,  like  that  of  root  and  stem,  radially  symmetrical 
about  its  organic  axis.  The  designation  of  the  continuous 
cylinder  of  root  and  stem  as  a  stele  and  of  each  bundle  or 
the  whole  bundle  system  of  the  leaf  as  a  schistostele  or 
meristele  is  in  complete  accord  with  this  general  fact.  But 
we  must  not  disguise  from  ourselves  that  both  the  stele  and 
the  meristele  may  not  exist  in  the  adult  as  sharply  separated 
structures. 

A.   G.   Tansley. 
( To  be  contimted. ) 


ON  SOME  APPLICATIONS  OF  THE  THEORY 
OF  OSMOTIC  PRESSURES  TO  PHYSIO- 
LOGICAL   PROBLEMS. 

PART    II. 

IN  my  previous  article  I  gave  some  account  of  a  research 
by  Heidenhain  in  which  this  observer,  after  drawing 
certain  deductions  from  the  theory  of  osmotic  pressures,  shows 
that  the  phenomena  of  absorption  from  the  intestinal  canal  are 
irreconcilable  with  these  deductions,  and  are  therefore  not 
susceptible  of  a  mechanical  explanation,  but  must  be  as- 
cribed to  the  active  intervention  of  cells.  Since  analogous 
problems  to  those  discussed  by  Heidenhain  are  continually 
coming  before  us  in  physiology,  it  is  important  that  we 
should  have  a  clear  idea  of  the  factors  which  are  involved 
in  the  passage  of  water  or  dissolved  substances  across 
membranes.  I  therefore  propose  to  reproduce  Heiden- 
hain's  statements,  and  then  to  consider  how  far  they  are 
true  for  the  special  cases  which  occur  in  the  body. 

These  statements  are  as  follows  : — 

i.  If  two  watery  solutions  with  the  same  osmotic  pres- 
sure are  separated  by  a  membrane  through  which  diffusion 
can  take  place,  no  change  in  volume  occurs  on  either  side 
of  the  membrane. 

2.  If  the  solutions  on  either  side  of  the  membrane  are  of 
unequal  osmotic  pressure,  water  passes  from  the  side  where 
the  pressure  is  less  to  the  side  where  the  osmotic  pressure 
is  greater. 

3.  The  osmotic  pressure  of  a  solution  is  equal  to  the  sum 
of  the  partial  pressures  of  the  various  dissolved  substances. 

4.  If  the  solutions  on  the  two  sides  of  the  membrane 
have  the  same  total  osmotic  pressure  but  unequal  partial 
pressures  of  their  various  constituents,  each  constituent  of 
the  solution  passes  from  the  side  where  it  has  the  higher 
partial  pressure  to  the  other  side.  No  change  in  the  volume 
of  water  on  the  two  sides  takes  place. 

Of  these  four  statements  only  one  (No.  3)  is  absolutely 


152  SCIENCE  PROGRESS. 

correct.  The  other  three  are  only  correct  under  certain 
defined  conditions  which  are  rarely  fulfilled  in  the  body. 
There  are  factors  at  work  which  have  been  practically  dis- 
regarded by  most  of  the  recent  workers  on  the  subject,  and 
which  may  tend  to  produce  movement  of  fluid  in  apparent 
opposition  to  the  difference  of  osmotic  pressure.  Instances 
of  such  cases  are  afforded  in  a  paper  by  Lazarus  Barlow,  to 
a  consideration  of  whose  work  we  shall  shortly  return. 

There  can  be  no  doubt  that  in  the  phenomena  of  trans- 
ference of  fluid  or  dissolved  substances  across  a  membrane 
the  nature  of  the  membrane  itself  is  all-important.  I  will, 
therefore,  shortly  run  through  the  various  modes  in  which 
interchanges  may  take  place  across  membranes  of  varying 
permeability.  We  shall  see  that  the  close  analogy  which 
exists  between  substances  in  solution  and  gases,  when 
dealing  with  "semi-permeable"  membranes,  is  also  borne 
out  by  experiment  when  used  to  predict  the  behaviour  of 
solutions  separated  by  such  permeable  membranes  as  occur 
in  the  body. 

The  simplest  case  is  that  in  which  two  fluids  are  sepa- 
rated by  a  perfect  semi-permeable  membrane  that  permits 
the  passage  of  water  but  is  absolutely  impermeable  to  dis- 
solved substances.  In  this  case  the  transference  of  water 
from  one  side  to  the  other  depends  entirely  on  the  difference 
of  osmotic  pressure  between  the  two  sides. 

m. 


A 

B 

If  we  suppose  two  vessels,  A  and  B,  separated  by  such 
a  membrane,  A  containing  a  solution  of  a  and  B  a  solution 
of  (5,  water  will  pass  from  A  to  B  so  long  as  the  osmotic 
pressure  of  /3  is  greater  than  the  osmotic  pressure  of  the 
solution  of  a.  If  B  be  subjected  to  a  hydrostatic  pressure 
greater  than  the  osmotic  difference  between  the  two  fluids, 
water  will  pass  from  B  to  A  until  the  force  causing  filtration 
or  transudation   (the  hydrostatic  pressure)   is  equal  to  the 


THE  THEORY  OF  OSMOTIC  PRESSURES.         153 

force  causing  absorption  into  B  (the  difference  of  osmotic 
pressures).  Under  no  circumstance  will  there  be  any  trans- 
ference of  salt  or  dissolved  substance  between  the  two  sides. 
Such  semi-permeable  membranes  as  this,  however,  rarely 
occur  in  the  body.  It  is  possible  that  the  external  layer  of 
the  cell-protoplasm  may  in  some  cases  resemble  the  proto- 
plasmic pellicle  of  plant-cells  in  possessing  this  "semi-per- 
meability "  ;  but  in  nearly  all  cases  where  we  have  a  mem- 
brane made  up  of  a  number  of  cells,  it  can  be  shown  that 
such  a  membrane  permits  the  free  passage  of  at  any  rate  a 
large  number  of  dissolved  substances. 

Let  us  now  consider  what  will  occur  when  the  two  solu- 
tions A  and  B  are  separated  by  a  membrane  which  permits  the 
free  passage  of  salts  and  water.  If  the  osmotic  pressure  of 
B  be  higher  than  A  at  the  commencement  of  the  experi- 
ment, the  force  tending  to  move  water  from  A  to  B  will  be 
equal  to  this  osmotic  difference.  But  there  is  at  the  same 
time  set  up  a  diffusion  of  the  dissolved  substances  from  B 
to  A  and  from  A  to  B.  The  result  of  this  diffusion  must 
be  that  there  is  no  longer  a  sudden  drop  of  osmotic  pressure 
from  B  to  A,  and  the  result  of  the  primary  osmotic  difference 
on  the  movement  of  water  will  be  minimised  in  proportion 
to  the  freedom  of  diffusion  which  takes  place  through  the 
membrane.  Now  let  us  take  a  case  in  which  A  and  B  re- 
present equimolecular  and  isotonic  solutions  of  o  and  /3. 
It  is  evident  that  the  movement  of  water  into  A  will  vary 
as  Ap  -  Bpl  =  O.  But  diffusion  also  occurs  of  a  into  B  and 
of  (3  into  A.  Now  the  amount  of  substance  diffusing  from 
a  solution  is  proportional  to  the  concentration,  and  there- 
fore to  its  osmotic  pressure,  as  well  as  to  its  diffusion 
coefficient. 

Hence  the  amount  of  a  diffusing  into  B  will  vary  as 
Aft  .  ak  (when  k  is  the  diffusion  coefficient). 

In  the  same  way  the  amount  of  (3  diffusing  into  A  will 
vary  as  Bp,  (5k'. 

Hence  if  ak  is  greater  than  (3k',  i.e.,  if  a  is  more  diffusible 
than  (3,  the  initial  result  must  be  that  a  greater  number  of 

1  Ap  =  osmotic  pressure  of  A,  etc. 


154  SCIENCE  PROGRESS. 

molecules  of  o  will  pass  into  B  than  of  /3  into  A.  Hence 
the  solutions  on  the  two  sides  of  the  membrane  will  be  no 
longer  equimolecular,  but  the  total  number  of  molecules  of 
a  +  (3  in  B  will  be  greater  than  the  number  of  molecules  of 
a  +  j3  in  A,  and  this  difference  will  be  most  marked  in  the 
layers  of  fluid  nearest  the  membrane.  The  result  therefore 
of  the  unequal  diffusion  of  the  two  substances  is  to  upset 
the  previous  equality  of  osmotic  pressures.  The  layer  of 
fluid  on  the  B  side  of  the  membrane  will  have  an  osmotic 
pressure  greater  than  the  layer  of  fluid  in  immediate  contact 
with  the  A  side  of  the  membrane,  and  there  will  thus  be  a 
movement  of  water  from  A  to  B.  Hence  if  we  have  two 
equimolecular  and  isotonic  solutions  of  different  substances 
separated  by  a  membrane  permeable  to  the  dissolved  sub- 
stances, there  will  be  an  initial  movement  of  fluid  towards 
the  side  of  the  less  diffusible  substance. 

We  have  an  exact  parallel  to  this  in  Graham's  familiar 
experiment  in  which  a  porous  pot  filled  with  hydrogen  is 
connected  by  a  vertical  tube  with  mercury.  In  consequence 
of  the  more  rapid  diffusion  outwards  of  the  hydrogen  than 
of  atmospheric  air  inwards,  the  pressure  within  the  pot  sinks 
below  that  of  the  surrounding  atmosphere,  and  the  mercury 
rises  several  inches  in  the  tube.  We  must  therefore  con- 
clude that  even  when  the  two  solutions  on  either  side  of  the 
membrane  are  isotonic,  there  may  be  a  movement  of  fluid 
from  one  side  to  the  other  with  a  performance  of  work  in 
the  process. 

The  experimental  proof  of  the  truth  of  this  argument  is 
to  be  found  in  a  recent  paper  by  Dr.  Lazarus  Barlow. 
This  observer — after  pointing  out  that  the  huge  total 
osmotic  pressures  of  the  salt  solutions  in  the  body  can  very 
seldom  come  into  play — insists  on  the  fact  that  the  most  im- 
portant point  to  study  in  this  regard  is  the  initial  changes 
that  take  place  between  dissimilar  fluids  separated  by  a 
membrane — as  he  terms  it — the  initial  rate  of  osmosis.  For 
this  purpose  he  employs  a  funnel,  the  neck  of  which  is  pro- 
longed into  a  capillary  tube,  while  on  the  mouth  is  tied  a 
piece  of  peritoneal  membrane.  The  funnel  is  filled  with 
the  solution  whose  osmotic  attraction  for  water  it  is  wished 


THE  THEORY  OF  OSMOTIC  PRESSURES.         155 

to  measure,  and  its   mouth  covered  with  the   membrane  is 
immersed  in  distilled  water  or  in  dilute  serum. 

The  experiments  which  are  the  most  interesting  are 
those  in  which  decinormal  solutions  of  glucose,  urea, 
sodium  chloride  were  compared  as  to  their  initial  rates  of 
osmosis,  the  outer  fluid  being  water.  He  concludes  from 
his  experiments  that,  in  the  case  of  prepared  peritoneal 
membrane,  the  initial  rates  of  osmosis  of  glucose,  sodium 
chloride  and  urea  in  equimolecular  solutions  do  not  corre- 
spond to  the  ratio  between  their  final  osmotic  pressures  (as 
estimated  by  the  depression  of  freezing-point),  but  the 
initial  rate  of  osmosis  of  glucose  {i.e.,  the  rate  with  which 
water  passes  into  this  solution)  is  greater  than  that  of 
sodium  chloride,  and  the  initial  rate  of  osmosis  of  sodium 
chloride  greater  than  that  of  urea. 

In  these  experiments  the  only  two  solutions  which 
are  strictly  comparable  are  those  of  urea  and  glucose 
(A  =  0*189°  C),  since  the  decinormal  Na  CI  solution  had 
nearly  double  the  osmotic  pressure  of  these  two  (A  =  0*35 1). 
In  three  typical  experiments,  each  of  which  lasted  three 
hours,  the  average  rates  at  which  the  fluid  in  the  funnel 
increased  in  volume  during  the  first  hour  were  :  in  the  case 
of  glucose,  7!  mm.  in  five  minutes  ;  in  the  case  of  sodium 
chloride,  43  mm.  ;  and  in  the  case  of  urea,  iJT  mm. 
These  figures  are  evidently  not  proportional  to  the  differ- 
ence of  osmotic  pressures  between  the  fluid  and  the  funnel 
and  the  water  in  the  reservoir.  But  we  have  already  seen 
that  the  moving  force  is  not  the  total  difference  of  pressure 
between  the  fluids  in  the  vessels  on  either  side  of  the 
membrane,  but  the  difference  of  pressure  between  the 
layers  of  fluid  in  immediate  contact  with  each  side  of  the 
membrane.  The  fall  of  osmotic  pressure  across  the  thick- 
ness of  the  membrane  varies  inversely  as  the  rate  of 
diffusion  of  the  dissolved  substance.  The  question  arises 
therefore  whether  the  results  obtained  by  Lazarus  Barlow 
can  be  accounted  for  by  differences  in  the  rate  of  diffusion. 
In  the  carefully  worked-out  tables  by  this  observer  we  have 
all  the  data  necessary  to  decide  the  question.  In  the  case 
of  glucose,  the  freezing-point  of  the  solution  at  the  begin- 


156  SCIENCE  PROGRESS. 

ning  of  the  experiment  was  -  o'i8q°  ;  at  the  end  of  the  three 
hours'  experiment  it  was  —  ot  JJ°  C. — corresponding  to  a 
loss  of  6  per  cent,  of  the  dextrose.  In  the  case  of  the 
urea,  the  freezing-point  at  the  beginning  was  "189°,  and  at 
the  end  was- 0*154°  C,  a  loss  of  18  per  cent.  Here  then 
the  initial  rate  of  osmosis  of  the  glucose  was  about  five 
times  that  of  the  urea ;  the  loss  by  diffusion  of  the  glucose 
was  about  one-third  that  of  the  urea.  In  the  case  of  the 
sodium  chloride  the  loss  amounted  to  22  per  cent.  ;  but 
here  the  total  difference  of  osmotic  pressure  was  very 
nearly  double  that  of  the  other  two  solutions,  and  the  result 
is  that  the  initial  rate  of  osmosis  of  the  sodium  chloride  takes 
an  intermediate  place  between  that  of  urea  and  that  of 
glucose. 

In  this  paper  the  results  of  another  experiment  are 
given  to  show  that  osmosis  may  occur  from  a  fluid  having 
a  higher  final  osmotic  pressure  towards  a  fluid  having  a 
lower  final  osmotic  pressure.  If,  for  example,  equimolecu- 
lar  solutions  of  sodium  chloride  and  glucose  be  separated 
by  a  peritoneal  membrane,  the  osmotic  flow  will  take  place 
from  the  fluid  having  the  higher  final  osmotic  pressure — 
sodium  chloride.  We  might  compare  with  this  experiment 
the  results  of  separating  hydrogen  at  one  atmosphere's 
pressure  from  oxygen  at  two  atmospheres'  pressure  by 
means  of  a  plate  of  graphite.  In  this  case  the  initial  result 
will  be  a  still  further  increase  of  pressure  on  the  oxygen 
side  of  the  diaphragm — a  movement  of  gas  against  pres- 
sure taking  place  in  consequence  of  the  greater  diffusion 
velocity  of  hydrogen. 

So  far  we  have  only  considered  the  behaviour  of  solu- 
tions when  separated  by  a  membrane,  the  permeability  of 
which  to  salts  is  comparable  to  that  of  water  ;  so  that  the 
passage  of  salts  through  the  membrane  depends  merely  on 
the  diffusion  rates  of  the  salts.  There  can  be  no  doubt, 
however,  that  we  might  get  analogous  movements  of  fluid 
against  total  osmotic  pressure  determined,  not  by  the 
diffusibility  of  the  salts,  but  by  the  permeability  of  the  mem- 
brane for  the  salts — a  permeability  which  may  depend  on  a 
state  of  solution  or  attraction  existing  between  membrane 


THE  THEORY  OF  OSMOTIC  PRESSURES.         157 

and  salts.  We  have  a  familiar  analogue  to  such  a  condition 
of  things  in  the  passage  of  gases  through  an  india-rubber 
sheet.  If  two  bottles,  one  containing  carbonic  acid,  the 
other  hydrogen,  be  separated  by  a  sheet  of  india-rubber, 
C03  passes  into  the  hydrogen  bottle  more  quickly  than 
hydrogen  can  pass  out  into  the  C02  bottle,  so  that  a  dif- 
ference of  pressure  is  created  between  the  two  bottles,  and 
the  rubber  bulges  into  the  C02  bottle.  We  might,  in  the 
same  way,  conceive  of  a  membrane  which  permitted  the 
passage  of  dextrose  more  easily  than  that  of  urea.  With 
such  a  membrane,  experiments  conducted  in  the  same  way 
as  Dr.  Barlow's,  would  lead  to  diametrically  opposite  re- 
sults. The  importance  of  the  membrane  in  determining 
the  direction  of  the  osmotic  passage  of  fluid  is  well  illustrated 
by  Raoult's  experiments.  When  alcohol  and  ether  were 
separated  by  an  animal  membrane,  alcohol  passed  into  the 
ether,  whereas  if  vulcanite  were  employed  for  the  dia- 
phragm, the  osmotic  flow  was  in  the  reverse  direction, 
and  an  enormous  pressure  was  set  up  on  the  alcohol  side  of 
the  diaphragm. 

Here  we  have  a  possible  clue  to  the  "explanation"  of 
many  phenomena  of  cell  activity,  to  which  the  term  "  vital" 
is  often  assigned.  In  the  swimming-bladder  of  fishes,  for 
instance,  we  find  a  gas  which  is  extremely  rich  in  oxygen, 
and  the  oxygen  is  said  to  have  been  secreted  by  the  cells 
lining  the  bladder.  It  is,  however,  very  possible  that  the 
processes  here  may  be  exactly  analogous  to  Graham's 
atmolysis,  and  that  the  bladder  may  represent  a  perfected 
form  of  Graham's  india-rubber  bag. 

The  next  point  to  be  considered  is  the  passage  of  a 
dissolved  substance  across  membranes  in  consequence  of 
differences  in  the  partial  pressure  of  the  substance  in  ques- 
tion on  the  two  sides  of  the  membrane.  Great  stress  is 
laid  by  Heidenhain  and  his  pupil  Orlow  on  the  fact  that 
in  the  peritoneal  cavity,  as  well  as  from  the  intestine,  salt 
may  be  taken  up  from  fluids  containing  a  smaller  percentage 
of  this  substance  than  does  the  blood  plasma,  and  they 
regard  this  absorption  as  pointing  indubitably  to  an  active 
intervention  of  living  cells  in  the  process.     This  argument 


158 


SCIENCE  PROGRESS. 


requires  examination.  Supposing  the  two  vessels  A  and  B 
to  be  separated  by  a  membrane  which  offers  free  passage 
to  water,  and  a  difficult  passage  to  salts.      Let  A  contain  '5 


n 


A 


B 


per  cent,  salt  solution  and  B  a  solution  isotonic  with  a  1 
per  cent.  Na  CI,  but  containing  only  '65  per  cent,  of  this 
salt,  the  rest  of  its  osmotic  tension  being  due  to  other  dis- 
solved substances.  If  the  membrane  were  absolutely  "  semi- 
permeable," water  would  pass  from  A  to  B  until  the  two 
fluids  were  isotonic,  i.e.,  until  A  contained  1  per  cent.  Na  CI 
(we  may  regard  volume  of  B  as  infinitely  great  to 
simplify  the  argument).  If,  however,  the  membrane  per- 
mitted passage  of  salt,  the  course  of  events  might  be  as 
follows  :  At  first  water  would  pass  out  of  A,  and  salt  would 
diffuse  in  until  the  percentage  of  Na  CI  in  A  was  equal 
to  that  in  B.  There  would  now  be  an  equal  partial  pres- 
sure of  Na  CI  on  the  two  sides  of  the  membrane,  but  the 
total  osmotic  pressure  of  B  would  still  be  higher  than  A. 
Water  would  therefore  still  continue  to  pass  from  A  to  B 
more  rapidly  than  the  other  ingredients  of  B  could  pass 
into  A.  As  soon,  however,  as  more  water  passed  only 
from  A,  the  percentage  of  N a  CI  in  A  would  be  raised 
above  that  in  B.  The  extent  to  which  this  occurs  will 
depend  on  the  impermeability  of  the  membrane.  As  soon, 
however,  as  the  Na  CI  in  A  reaches  a  certain  concentration 
it  will  pass  over  into  B,  and  this  will  goon  until  equilibrium 
is  established  between  A  and  B.  Extending  this  argument 
to  the  conditions  obtaining  in  the  living  body,  we  may  con- 
clude that  neither  the  raising  of  the  percentage  of  a  salt 
in  any  fluid  above  that  of  the  same  salt  in  the  plasma,  nor 
the  passage  of  a  salt  from  a  hypotonic  fluid  into  the  blood 
plasma,  can  afford  in  itself  any  proof  of  an  active  interven- 
tion of  cells  in  the  process. 


THE  THEORY  OF  OSMOTIC  PRESSURES.         159 

Thus  in  the  case  of  the  pleura  we  seem  to  have  a  mem- 
brane which  is  very  imperfectly  semi-permeable.  It  is  per- 
meable to  salts,  but  presents  rather  more  resistance  to  their 
passage  than  to  the  passage  of  water.  Hence  on  injecting 
•5  per  cent.  Na  CI  solution  into  the  pleural  cavity  water 
passes  from  the  pleural  fluid  into  the  blood,  until  the  per- 
centage of  sodium  chloride  in  the  fluid  is  raised  perceptibly 
above  that  in  the  blood  plasma.  The  limit  of  the  resistance 
of  the  pleural  membrane  to  the  passage  of  salt  is,  however, 
soon  reached,  and  then  salt  passes  from  pleural  fluid  into 
blood  ;  but  in  every  case  this  passage  is  from  a  region  of 
higher  to  a  region  of  lower  partial  pressure.  Hence  at 
a  certain  stage  of  the  experiment  we  find  a  higher  percentage 
of  salt  in  the  pleura  than  in  the  blood-vessels,  although 
the  total  amount  of  salt  in  the  pleural  fluid  is  less  than 
that  originally  put  in,  or,  in  other  words,  salt  has  been 
absorbed. 

We  have  already  seen  that  the  effective  osmotic  pressure 
of  a  substance,  i.e.,  its  power  of  attracting  water  across  a 
membrane,  varies  inversely  as  its  diffusibility,  or  as  the 
permeability  of  the  membrane  to  it.  What  then  will  be 
the  effect  supposing  that  on  one  side  of  the  membrane  we 
place  some  substance  in  solution  to  which  the  membrane 
is  impermeable  ? 

We  will  suppose  that  A  and  B  both  contain  1  per  cent. 
Na  CI,  but  that  B  contains  in  addition  some  substance  x  to 
which  the  membrane  is  impermeable.  Since  the  osmotic 
pressure  of  B  is  higher,  by  the  partial  pressure  of  x,  than 
that  of  A,  fluid  will  pass  from  A  to  B  by  osmosis.  But  the 
consequence  of  this  passage  of  water  will  be  to  concentrate 
the  Na  CI  in  A,  so  that  the  partial  pressure  of  this  salt  in 
A  is  greater  than  in  B.  Na  CI  will  therefore  diffuse  from 
A  to  B  with  the  result  that  the  former  difference  of  total 
osmotic  pressure  will  be  re-established.  Hence  there  will 
be  a  continual  passage  of  both  water  and  salt  from  A  to  B, 
until  B  has  absorbed  the  whole  of  A.  This  result  will 
be  only  delayed  if  the  osmotic  pressure  of  A  is  at  first 
higher  than  B,  in  consequence  of  a  greater  concentration 
of  Na  CI  in  A.      There  may  be  at  first  a  flow   of  fluid 


160  SCIENCE  PROGRESS. 

from  B  to  A,  but  as  soon  as  the  Na  CI  concentration  on 
the  two  sides  has  become  the  same  by  diffusion  the  power 
of  x  to  attract  water  from  the  other  side  will  make  itself 
felt,  and  this  attraction  will  be  proportional  to  the  osmotic 
pressure  of  x. 

We  have  an  example  of  such  a  process  in  the  absorption 
of  salt  solutions  from   the  connective  tissues  by  the  blood- 
vessels, as  well  as  in  the  absorption   of  the  normal  tissue 
lymph.      The  capillaries  of  the   connective   tissues  of  the 
limbs  and  peripheral  parts  of  the  body  are  almost  imperme- 
able to  proteids.      In  consequence  of  this  impermeability  the 
fluid  which  is  transuded  from  the  capillaries  under  pressure 
contains  very  little  proteid,  whereas  it  contains  exactly  the 
same  proportion  of  salts  as  does  the  blood  plasma.     It  seems 
probable  therefore  that  the   proteid  left  in  solution  in  the 
capillaries  must  exert  a  certain  osmotic  attraction   on  the 
salt    solution     outside     the     capillaries.        It    is    easy    to 
measure  this  attractive  force.      If  blood  serum  be  placed  in 
a  small  thistle  funnel,  on  the  open  end  of  which  is  stretched 
a  layer  of  membrane  soaked  in   gelatine,  and  the  inverted 
funnel  be  immersed  into  salt  solution  which   is  isotonic  or 
even  hypertonic  as  compared  with  the  serum,  measured  by 
the  freezing-point,  within  the  next  two  to  four  days  fluid 
will  pass  into  the  funnel  and  rise  up  in  its  capillary  stem  to 
a    considerable    height.       I    have  found    that  the    osmotic 
pressure  of  the  non-diffusible  constituents  of  blood  serum 
measured  in  this  way  amounts  to  between  30  mm.  and  40  mm. 
Hg.  Now  although  this  osmotic  pressure  is  so  small,  it  is  of  an 
order  of  magnitude  comparable  with  that  of  the  hydrostatic 
pressure  in  the  capillaries.      This  fact  is   of  importance  in 
that,  whereas  the  capillary  pressure  determines  transudation 
from    the    vessels,    the    effective   osmotic    pressure    of   the 
serum    (proteids  ?)    determines   absorption    by    the    blood- 
vessels.     Moreover  the  osmotic  attraction  of  the  serum  for 
the    extravascular    fluid   will  be    proportional   to    the  force 
expended  in  the  production  of  this   extravascular  fluid,  so 
that    at    any    given     time   there    must  be  a    balance    be- 
tween the  hydrostatic   pressure  in   the  capillaries  and    the 
production    or    absorption   of  fluid   from    the  extravascular 


THE  THEORY  OF  OSMOTIC  PRESSURES.         161 

spaces — a  balance  which  is  known  to  obtain  under  physio- 
logical conditions.  If  we  increase  the  volume  of  circulating 
fluid  we  increase  intracapillary  pressure  and  the  blood 
volume  tends  to  diminish  in  consequence  of  increased 
transudation.  If  we  diminish  the  capillary  pressure  by 
bleeding  the  animal,  absorption  will  predominate  over  exu- 
dation, and  the  volume  of  circulating  fluid  will  tend  to 
increase  towards  its  normal  amount. 

From  this  cursory  study  of  some  of  the  simplest  examples 
of  transference  of  fluids  and  salts  across  membranes,  we 
may  draw  certain  conclusions  as  to  the  main  factors  which 
are  of  importance  for  the  process. 

These  are  :  (i)  The  permeability  of  the  membrane  to  the 
dissolved  substances.  This  permeability  may  be  of  the 
same  character  as  the  permeability  of  water,  in  which  case 
the  rates  of  passage  of  the  dissolved  substances  across  the 
membrane  vary  as  their  diffusibilities,  and  are  therefore 
probably  some  function  of  their  molecular  weights.  On  the 
other  hand  the  membrane  may  exhibit  a  certain  attraction 
for,  or  power  of  dissolving,  some  dissolved  substances  to  the 
exclusion  of  others,  in  which  case  there  will  be  no  relation 
between  the  diffusibilities  and  rates  of  passage  of  the  dis- 
solved substances. 

(2)  The  osmotic  pressure  of  the  solutions.  It  is  evident 
that  the  rules  deduced  by  Heidenhain  from  the  accepted 
theory  of  osmotic  pressures,  and  quoted  at  the  beginning  of 
this  article,  are  fallacious  in  consequence  of  a  too  narrow  con- 
sideration of  this  second  factor  to  the  exclusion  of  the  first. 
At  the  same  time  it  must  be  confessed  that  our  knowledge 
of  the  permeability  of  different  membranes  to  different 
substances,  as  well  as  of  the  factors  on  which  this  per- 
meability depends,  is  still  in  an  embryonic  condition. 
There  can  be  no  doubt  that  a  careful  exploration  of  this 
field  of  research  would  yield  results  not  only  interesting 
to  the  physicist,  but  also  of  incalculable  value  to  the 
physiologist  in  his  investigation  of  the  phenomena  of 
living  things. 


11 


162  SCIENCE  PROGRESS. 


BIBLIOGRAPHY. 

(i)  Heidenhain.     Neue  Versuche  liber  die  Aufsaugung  im  Diinn- 
darm.     Pfiiigers  Archiv,  lvi.,  p.  600,  1894. 

(2)  LAZARUS  BARLOW.    Observations  upon  the  Initial  Rates  of  Os- 

mosis of  certain  Substances  in  Water  and  in  Fluids  containing 
Albumen.    Journ.  of  Phys.,  vol.  xix.,  p.  140,  1895. 

(3)  ORLOW.     Einige  Versuche  iiber  die  Resorption   in  der  Bauch- 

hohle.     Pfiiigers  Archiv,  vol.  lix.,  p.  170,  1894. 

(4)  Leathes  and  Starling.     On  the  Absorption  of  Salt  Solutions 

from  the  Pleural  Cavities.     Journ.  of  Phys.,  vol.  xviii.,  1895. 

(5)  Leathes.     Some  Experiments  on  the  Exchange  of  Fluid  be- 

tween the  Blood  and  Tissues.    Journ.  of  Phys.,  vol.  xix.,  p.  1, 

1895. 

(6)  HAMBURGER.    Ueber  die  Regelung  der  osmotischen  Spannkraft 

von  Fliissigkeiten  in  Bauch  und  Pericardialhohle.     Du  Bois 
Archiv,  p.  281,  1895. 

(7)  STARLING.     On  the  Absorption  of  Isotonic  Solutions  from  the 

Connective  Tissues.    Journ.  of  Phys.,  1896. 

Ernest  H.   Starling. 


Science  |)ragre$s. 


No.  27.  May,   1896.  Vol.  V. 


THE   PAST,  PRESENT  AND  FUTURE  WATER 
SUPPLY  OF  LONDON.1 

IN  a  discourse  to  the  Members  of  the  Royal  Institution 
on  the  subject  of  the  Metropolitan  Water  Supply 
nearly  thirty  years  ago,  I  stated  that  out  of  every  thousand 
people  existing  upon  this  planet  at  that  moment,  three 
lived  in  London ;  and,  as  the  population  of  London 
has  in  the  meantime  doubtless  grown  at  a  more  rapid  rate 
than  that  of  the  rest  of  the  world,  it  will  probably  be  no 
exaggeration  to  say  that  now,  out  of  every  thousand  people 
alive  on  this  earth,  four  live  in  London  ;  and  therefore  any 
matter  which  immediately  concerns  the  health  and  comfort 
of  this  vast  mass  of  humanity  may  well  merit  our  most 
earnest  attention.  Amongst  such  matters  that  of  the 
supply,  in  sufficient  quantity,  of  palatable  and  wholesome 
water  is  certainly  not  the  least  in  importance. 

It  is  not  therefore  surprising  that  this  subject  has 
received  much  attention  from  several  Royal  Commissions, — 
notably  from  the  Royal  Commission  on  Water  Supply  of 
1867,  presided  over  by  the  Duke  of  Richmond,  the  Royal 
Commission  on  the  Pollution  of  Rivers  and  Domestic 
Water  Supply  of  Great  Britain,  presided  over  by  the  late 
Sir  William  Dennison,  of  which  I  had  the  honour  to  be  a 
member  ;  and  lastly  the  Royal  Commission,  appointed  in 
1892  to  inquire  into  the  Water   Supply  of  the  Metropolis, 

1  A  discourse  delivered  at  the  Royal  Institution,  21st  February,  1896. 

12 


1 64  SCIENCE  PROGRESS. 

of  which  Lord  Balfour  of  Burleigh  was  Chairman,  and  of 
which  Professor  Dewar  was  a  member. 

The  Royal  Institution  has  also  for  nearly  three-quarters 
of  a  century  been  prominently  connected  with  the  investiga- 
tion and  improvement  of  the  Metropolitan  Water  Supply  ; 
no  less  than  four  of  our  Professors  of  Chemistry  having 
been  successively  engaged  in  this  work,  viz.,  Professors 
Brande,  Odling,  Dewar,  and  myself,  whilst  three  of  them 
have  been  members  of  the  Royal  Commissions  just 
mentioned.  I  may  therefore  perhaps  be  excused  for 
accepting  the  invitation  of  our  Secretary  to  bring  the 
subject  under  your  notice  for  the  third  time. 

On  the  present  occasion  I  propose  to  consider  it  from 
three  points  of  view,  viz.,  the  past,  the  present  and  the 
future  ;  and,  for  reasons  which  will  appear  hereafter,  I  shall 
divide  the  past  from  the  present  at,  or  about,  the  year  1883, 
and  will  not  go  back  farther  than  the  year  1828,  when  Dr. 
Brande,  Professor  of  Chemistry  in  the  Royal  Institution  ; 
Mr.  Telford,  the  celebrated  engineer  ;  and  Dr.  Roget, 
Secretary  of  the  Royal  Society  were  appointed  a  Royal 
Commission  to  inquire  into  the  quality  and  salubrity  of  the 
water  supplied  to  the  Metropolis. 

The  Commissioners  made  careful  examinations  and 
analyses,  and  reported  as  follows  :  "  We  are  of  opinion  that 
the  present  state  of  the  supply  of  water  to  the  Metropolis 
is  susceptible  of,  and  requires,  improvement  ;  that  many  of 
the  complaints  respecting  the  quality  of  the  water  are  well 
founded,  and  that  it  ought  to  be  derived  from  other  sources 
than  those  now  resorted  to,  and  guarded  by  such  restrict- 
tions  as  shall  at  all  times  ensure  its  cleanliness  and  purity. 
(At  this  time  the  water  was  pumped  from  the  Thames 
between  London  Bridge  and  Battersea.)  To  obtain  an 
effective  supply  of  clear  water  free  from  insects  and  all 
suspended  matter,  we  have  taken  into  consideration  various 
plans  of  filtering  the  river  water  through  beds  of  sand  and 
other  materials  ;  and  considering  this,  on  many  accounts,  as  a 
very  important  object,  we  are  glad  to  find  that  it  is  perfectly 
possible  to  filter  the  whole  supply,  and  this  within  such 
limits,  in  point  of  expense,  as  that  no  serious  objection  can 


THE  WATER  SUPPLY  OF  LONDON.  165 

be  urged  against  the  plan  on[  that  score  ;  and  with  such 
rapidity  as  not  to  interfere  with  the  regularity  of  service." 

Before  the  year  i82g,  therefore,  the  river  water  supplied 
to  London  was  not  filtered  at  all  ;  but  after  the  issue  of 
this  report,  the  Companies  set  themselves  earnestly  to  work 
to  improve  the  quality  of  the  water  by  filtration. 

The  first  filter,  on  a  working  scale,  was  constructed  and 
brought  into  use  by  the  Chelsea  Water  Company  in  the 
year  1829.  But  even  as  late  as  1850  only  three  out  of  the 
seven  principal  companies  filtered  the  river  water  which 
they  delivered  in  London  ;  and  it  was  not  until  1856  that 
filtration  was  made  compulsory  by  Act  of  Parliament, 
whilst  it  can  scarcely  be  doubted  that,  between  this  date  and 
the  year  1868,  when  my  observations  on  turbidity  were  first 
commenced,  the  operation  was  very  imperfectly  performed. 

In  the  year  1832,  and  again  in  1849,  London  was 
severely  visited  by  epidemic  cholera,  and  the  agency  of 
drinking  water  in  spreading  the  disease  forced  itself  upon 
the  attention  of  the  observant  portion  of  the  medical  pro- 
fession. It  was  Dr.  Snowe,  however,  who  in  August, 
1849,  first  formally  enunciated  the  doctrine  that  drinking 
water  polluted  by  choleraic  matters  is  the  chief  mode  by 
which  cholera  is  propagated. 

Received  at  first  with  incredulity,  this  doctrine  was 
supported  by  numerous  facts,  and  it  soon  caused  renewed 
attention  to  be  directed  to  the  quality  of  the  water  then 
being  supplied  to  the  Metropolis  ;  with  the  result  that  the 
intakes  of  the  various  Companies  drawing  from  rivers 
were,  one  after  another,  removed  to  positions  above  the 
reach  of  tidal  influence  ;  the  Thames  water  being  with- 
drawn from  the  river  above  Teddington  Lock,  and  the  Lea 
water  at  Ponder's  End,  above  the  tidal  reaches  of  that  river. 

In  every  visitation  of  Asiatic  cholera  to  London,  the 
water  supply  was  either  altogether  unfiltered  or  imperfectly 
filtered,  besides  being  derived  from  highly  polluted  parts 
of  the  Thames  and  Lea  ;  and  the  enormous  loss  of  life, 
amounting  in  the  aggregate  to  nearly  36,000  people,  can 
only  be  attributed  to  this  cause.  It  has  been  abundantly 
proved  that  efficient  filtration  is  a  perfect  safeguard  against 


1 66  SCIENCE  PROGRESS. 

the  propagation  of  the  disease,  and  since  the  year  1854  no 
case  of  Asiatic  cholera  in  London  has  been  traced  to  the 
use  of filtered  river  water. 

These  are  the  results  arrived  at  by  the  most  general 
investigation  of  the  subject.  They  show  that  in  every 
epidemic,  the  mortality  varied  directly  with  the  intensity  of 
the  drainage  pollution  of  the  water  drunk  by  the  people  ; 
but  if  time  permitted,  a  more  detailed  study  of  the 
statistics  in  both  epidemics  would  demonstrate,  much  more 
conclusively,  this  connection  between  cholera  mortality  and 
the  pollution  of  drinking  water — a  connection  which  has  quite 
recently  been  terribly  emphasised  in  the  case  of  Hamburg. 

Such  is  the  verdict  with  regard  to  cholera,  and  the 
same  is  true  of  that  other  great  water-borne  disease  typhoid 
fever.  But,  unlike  cholera,  this  disease  is  disseminated  in 
several  other  ways,  and  its  presence  or  absence  in  any 
locality  may  not,  of  necessity,  have  any  connection  with 
drinking  water,  as  is  strikingly  shown  by  the  health 
statistics  of  Manchester. 

There  is  no  evidence  whatever  that,  since  the  year 
1869,  when  typhoid  fever  appeared  for  the  first  time  as  a 
separate  disease  in  the  Registrar  General's  reports,  it  has 
been  conveyed  by  the  water  supply  of  the  Metropolis. 
An  inspection  of  the  diagram  (No.  1)  shows,  it  is  true,  a 
greater  proportional  mortality  during  the  period  of  imperfect 
filtration  than  during  the  later  period  ;  that  is  to  say  from 
1883  when  the  process  began  to  be  performed  with  uniform 
efficiency  ;  but  the  plotting  of  a  similar  curve  for  the  deaths 
by  typhoid  in  Manchester  shows  that  this  disease  arises  from 
other  causes  than  polluted  water,  since  the  water  supply 
of  Manchester,  derived  as  it  is  from  mountain  sources,  is 
above  all  suspicion  of  this  kind.  These  other  causes  have 
during  the  last  ten  years  been  much  mitigated  in  London 
by  various  sanitary  improvements ;  whilst,  as  shown  in 
the  diagram,  there  has  been  no  corresponding  mitigation 
in  Manchester. 

Although  very  soon  after  the  year  1856  all  the  water 
supplied  to  the  Metropolis  was  obtained  from  sources  much 
less  exposed  to  drainage  pollution,  it  was  still  very  carelessly 


THE  WATER  SUPPLY  OF  LONDON. 


167 


filtered.  Previous  to  the  year  1868,  there  are  no  records 
of  the  efficiency,  or  otherwise,  of  the  filtration  of  the 
Metropolitan  water  supply  derived  from  rivers,  as  dis- 
tinguished from  deep  wells,  the  water  of  which  is  perfectly 
clear  without  filtration. 

It  was  in  the  year  1868  that  I  first  began  to  examine 
the  water  supplied  to  the  Metropolis  from  rivers  with 
reference  to  efficiency  of  filtration.  I  n  that  year,  out  of 
eighty-four  samples  examined,  seven  were  very  turbid, 
eight  turbid,  and  ten  slightly  turbid,  so  that  altogether  no 
less  than  nearly  30  per  cent,  of  the  samples  were  those  of 
inefficiently  filtered  water.  The  Metropolitan  Water  Supply 
then,  up  to    the    year   1868,    may  be  shortly  described  as 


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derived  for  many  years  from  very  impure  sources  with 
either  no  filtration  at  all,  or  with  very  inefficient  filtration  ; 
and  afterwards,  when  the  very  impure  sources  were 
abandoned,  the  supply  was  still  often  delivered  in  a  very 
inefficiently  filtered  condition.  But,  after  the  establishment  of 
monthly  reports  on  the  filtration  of  the  river-derived  supplies, 
the  quality  of  these  waters  gradually  improved  in  this  most 
important  respect,  as  is  seen  from  diagram  No.  1.  In  this 
diagram,  the  continuous  line  with  dots  represents  the 
mortality  from  typhoid  in  Manchester,  the  broken  and 
eroped  line  the  contemporaneous  mortality  in  London,  and 
the  dotted  curve  the  degree  of  turbidity  of  the  London 
water  supply. 


1 68  SCIENCE  PROGRESS. 

These  observations  graphically  represented  in  the  dia- 
gram show  that,  at  the  time  they  were  commenced,  the 
filtering  operations  were  carried  on  with  considerable  care- 
lessness, and  that  this  continued,  though  to  a  less  extent, 
down  to  the  year  1883,  since  which  time,  and  especially 
since  1884,  the  efficiency  of  filtration  of  all  the  river  waters 
supplied  to  the  Metropolis  has  left  little  to  be  desired. 

What  is  it  then  that  separates  the  past  from  the  present 
water  supply  of  London  ?  In  the  first  place  there  is  the 
change  of  source — I  mean  the  change  in  position  of  the 
intakes  of  the  several  Companies  drawing  from  the  Thames 
and  Lea — and  the  total  abandonment  of  the  much-polluted 
river  Ravensbourne  by  the  Kent  Water  Company.  So 
long  as  the  water  supply  was  derived  from  the  tidal  reaches 
of  the  Thames  and  Lea,  receiving  as  these  reaches  did  the 
drainage  of  immense  populations,  the  risk  of  infection  from 
water-borne  pathogenic  organisms  could  scarcely  be  other- 
wise than  imminent ;  for,  although  we  now  know  efficient 
filtration  to  be  a  perfect  safeguard,  anything  short  of  effi- 
ciency must  be  attended  with  risk  in  the  presence  of  such 
extreme  pollution. 

Nevertheless,  the  line  of  demarcation  between  the  past 
and  the  present  water  supply  of  the  Metropolis  is,  in  my 
opinion,  to  be  drawn,  not  when  the  intakes  of  the  river 
companies  were  removed  to  positions  beyond  the  possibility 
of  pollution  by  the  drainage  of  London,  but  it  must  be  drawn 
at  the  time  when  efficient  filtration  was  finally  secured  and 
ever  since  maintained,  that  is  to  say,  in  the  year  1884. 

The  removal  of  turbidity  by  sand  filtration,  however, 
refers  only  to  suspended  matters  ;  but  there  are  sometimes 
objectionable  substances  in  solution  of  which  organic  matter 
is  the  most  important.  River  water  and  mountain  water, 
even  when  efficiently  filtrated,  contains  more  organic  matter 
than  spring  or  deep  well  water;  but  this  is  reduced  in  quantity 
by  storage  and  especially  by  filtration,  although  these  waters 
can  perhaps  never  be  brought  up  to  the  standard  of  organic 
purity  of  spring  and  deep  well  water. 


THE  WATER  SUPPLY  OF  LONDON. 


169 


THE    PRESENT   WATER   SUPPLY. 

At  present  London  is  supplied  with  water  from  four 
sources — the  Thames,  the  Lea,  the  New  River,  and  deep 
wells.  Of  these  the  deep  wells  yield  as  a  rule  the  purest 
water,  requiring  no  filtration  or  treatment  of  any  kind  before 
delivery  for  domestic  use.  The  river  waters,  on  the  other 
hand,  require  some  kind  of  treatment  before  delivery — 
storage,  subsidence  in  reservoirs,  and  filtration.  The  water 
from  the  Thames  is  abstracted  at  and  beyond  Hampton,  far 
above  the  reach  of  the  tide  and  London  drainage.  The 
water  from  the  Lea  is  taken  out  at  two  points,  viz.,  at  Angel 
Road  near  Chingford,  by  the  East  London  Water  Company, 


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and  above  Hertford  by  the  New  River  Company,  who 
convey  it  to  Green  Lanes  by  an  open  conduit  twenty-five 
miles  long,  called  the  New  River  Cut,  in  which  it  is  mixed 
with  a  considerable  volume  of  spring  and  deep  well  water. 

All  three  river  waters  are  affected  by  floods  and  are,  as 
raw  materials,  of  considerably  different  quality  as  regards 
organic  purity  (see  diagram  No.  2).  From  these  raw 
materials  by  far  the  largest  volume  of  the  Metropolitan 
Water  Supply  is  derived,  and  the  chemical  or  organic 
purity  of  the  water  sent  out  to  consumers  stands  in  direct 
relation  to  the  organic  purity  of  the  raw  material  used,  as 


170 


SCIENCE  PROGRESS. 


is  seen  from  the  diagrams  Nos.  3,  4  and  5,  which  show  the 
proportional  amounts  of  organic  elements  in  the  raw  and 
filtered  waters  ;  they  also  show  the  advantage  of  storage 
in  excluding  flood  water,  No.  4  shows  that  floods  in  March 


PROPORTIONAL     AMOUNT     OF     CRCANIC    ELEMENTS 
IN    THAMES    WATER 


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arid  August  were  circumvented,  but  not  in  November.  The 
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PROPORTIONAL   AMOUNT    OF    ORGANIC    ELEMENTS 
IN    RAW    LEA    AND     EAST    LONDON     COMPANY'S    WATER 


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Company's  water  during  the  nine  years  ending  December 

1876  being  taken  as  unity,  as  is  depicted  in  diagram  No.  5. 

Hitherto  I  have  spoken  of  chemical  purity  or  comparative 

freedom  from  organic  matter  only,  but  the  spread  of  diseases 


THE  WATER  SUPPLY  OF  LONDON. 


171 


such  as  cholera  and  typhoid  fever  through  the  agency  of 
drinking  water  has  no  connection  whatever  with  the  chemical 
or  organic  purity  of  the  water.  These  diseases  are  propa- 
gated by  living  organisms  of  extreme  minuteness,  to  which 
the  names  bacilli,  bacteria,  and  microbes  have  been  given, 
and  here  comes  the  important  question  how,  if  at  all,  does 
filtration  secure  immunity  from  these  water-borne  diseases  ? 
To  Dr.  Koch  of  Berlin,  we  are  indebted  for  the  answer 
to  this  question.  By  his  discovery  of  a  means  of  isolating 
and  counting  the  number  of  bacteria,  or  bacilli,  or  microbes 
and  their  spores  in  a  given  volume  of  water,  we  were,  for 
the  first  time,  put  into  possession  of  a  method  by  which  the 
condition  of  water  as  regards  these  living  organisms,  before 


PROPORTIONAL     AMOUNT     OF    ORGANIC     ELEMENTS 
IN    NEW    RIVER     AND     DEEP-WELL    WATERS. 

1835 


so 


No.  5. 

and  after  filtration,  can  be  determined  with  quantitative 
exactness.  The  enormous  importance  of  this  invention 
(which  was  first  made  known  and  practised  in  England  in 
1882  by  the  late  Dr.  Angus  Smith)  is  evident,  when  it  is 
borne  in  mind  that  the  living  organisms,  harmful  or  harm- 
less, contained  in  water  are  of  such  extreme  minuteness  as 
practically  to  defy  detection  by  ordinary  microscopical 
examination.  But  although  the  microscope  cannot  detect 
with  certainty  single  bacteria  or  their  spores,  even  the 
naked  eye  can  easily  discern  towns  or  colonies  consisting  of 
thousands  or  even  millions  of  such  inhabitants. 

Dr.   Koch's  method  accomplishes  at  once  two  things  : 
it    isolates,  in  the  first  place,  each    individual   microbe  or 


172  SCIENCE  PROGRESS. 

germ  ;  and,  secondly,  places  it  in  conditions  favourable  for 
its  multiplication  which  takes  place  with  such  amazing 
rapidity  that,  even  in  a  few  hours,  or  at  most  in  two  or 
three  days,  each  organism  will  have  created  around  itself 
a  visible  colony  of  innumerable  members — a  town  in  fact 
comparable  to  London  itself  for  population. 

By  operating  upon  a  known  volume  of  water,  such  as 
a  cubic  centimetre  for  instance,  the  number  of  separate 
organisms  or  their  spores,  in  a  given  volume  of  the  water 
under  investigation  can  thus  be  determined.  The  following 
is  the  method  now  adopted  in  carrying  out  Koch's  process 
for  the  bacterial  investigation  of  drinking  water : — 

i.    Preparation  of  the  nutritive  medium. 

2.  Sterilisation  of  the  medium. 

3.  Collection  of  the  sample  of  water  in  a  vacuous  tube 

afterwards  to  be  hermetically  sealed. 

4.  Transport   of    the    sample    to    the    bacteriological 

laboratory,  packed  in  ice  to  prevent  multiplica- 
tion. 

5.  Mixture   of  a  known  volume  of  the  water  sample 

with  the  nutrient  medium. 

6.  Casting  of  the  mixture  into  a  solid  plate. 

7.  Incubation  of  the  solid  plate. 

8.  Counting  of  the  colonies. 

9.  Examination  of  separate  colonies,  or  rather  of  the 

individual  members  under  the  microscope. 

Sometimes  the  cultivations  are  made  upon  a  plate  of 
the  substance  called  agar  which  resembles  isinglass,  and 
bears  a  temperature  of  blood  heat  without  melting. 

In  order  to  ascertain  the  effect  of  filtration  upon  the 
bacterial  quality  of  water,  it  is  absolutely  necessary  that 
the  sample  should  be  taken  immediately  after  it  has  passed 
through  the  filters  ;  for,  if  it  be  obtained  from  the  delivery 
mains  in  town,  that  is  to  say,  after  the  water  has  passed 
through  many  miles  of  pipes,  the  rapid  multiplication  of 
these  organisms,  except  in  very  cold  weather  is  such,  that 
a  water  which  contains  only  a  single  living  organism  per 
cubic  centimetre,   as  it  issues  from  the  filter,   may  contain 


THE  WATER  SUPPLY  OF  LONDON. 


173 


100  or  1000  in  the  same  volume  when,  after  several  hours, 
it  arrives  on  the  consumer's  premises. 

Now  what  is  the  effect  of  sand  filtration  as  carried  out 
by  the  various  Water  Companies  supplying  London  upon 
the  living  matter  contained  in  the  raw  river  water  ?  //  is 
simply  astounding :  water  containing  thousands  of  bacteria 
per  cubic  centimetre,  for  a  single  drop  of  Thames  water 
sometimes  contains  nearly  3000  separate  living  organisms, 
comes  out  from  the  sand  filters  with  fifty,  thirty,  ten,  or  even 
less  of  these  organisms  per  cubic  centimetre,  or  the  number 
of  microbes  in  a  single  drop  is  reduced  to  two  or  even  to  zero. 

MICROBES  IN  RAW  AND  FILTERED  THAMES 
WATER      1894. 


JANUARY 


FEBRUARY  MARCH  APRIL 


MAY  JUNE 


JULY  AUCUST  SEPTEMBER 


OCTOBER 


NOVEMBER  DECEMBER 

No.  6. 


MEAN 


Rather  less  than  one-tenth  of  the  total  volume  of  water 
supplied  to  London  is  derived  by  the  Kent  Water  Company 
from  deep  wells  in  the  chalk.  As  it  issues  from  the  porous 
rock  into  the  fissures  and  headings  of  these  wells,  this  water 
is,  in  all  probability,  absolutely  sterile  ;  but  by  the  time  it 
has  been  pumped  up  to  the  surface  it  usually  contains  a 
certain  number,  though  small,  of  microbes.  Thus,  during 
the  year  1892  it  contained  on  the  average  six  per  cubic 
centimetre  in  1893,  thirteen;  in  1894,  fifteen;  and  in 
1895,  eight. 

The  diagram  No.  6  shows  graphically  the  bacterial 
improvement    of   the    Thames   water    by  filtration    during 


i74  SCIENCE  PROGRESS. 

the  year  1894.  ^n  this  diagram  the  black  squares  represent 
the  number  of  microbes  in  a  given  volume  of  the  raw  water 
in  each  month,  and  the  white  centres  the  number  remaining 
in  the  same  volume  after  filtration. 

Although  deep  well  water  has,  from  a  bacterial  point 
of  view,  a  decided  advantage,  the  filtered  river  waters 
are  not  very  far  behind,  and  there  is  every  reason  to  believe 
that  with  the  improvements  which  are  now  being  carried  out 
by  the  various  river  Water  Companies,  the  Kent  Company's 
deep  well  water  will,  before  long,  be  run  very  hard  by  the 
other  supplies. 

By  the  examination  of  the  water  as  it  issues  from  the 
filters,  the  utmost  freedom  from  microbes,  or  maximum 
degree  of  sterility  of  each  sample  is  determined.  This 
utmost  freedom  from  bacterial  life  after  all  sources  of  con- 
tamination have  been  passed  is  obviously  the  most 
important  moment  in  the  history  of  the  water ;  for  the 
smaller  the  number  of  microbes  found  in  a  given  volume  at 
that  moment  the  less  is  the  probability  of  pathogenic  or 
harmful  organisms  being  present  ;  and  although  the  non- 
pathogenic may  afterwards  multiply  indefinitely  this  is  of 
no  consequence  in  the  primary  absence  of  the  pathogenic  ; 
but  it  is  only  fair,  in  describing  the  character  of  the  present 
water  supply  of  London,  to  say  that  not  a  single  pathogenic 
organism  has  ever  been  discovered  even  in  the  ^filtered 
water  as  it  enters  the  intakes  of  the  various  Companies, 
although  these  organisms  have  been  carefully  sought  for. 
It  is  sometimes  said  that  the  non-pathogenic  organisms 
found  in  water  may  be  beneficial  to  man  ;  but  this  idea  is 
not  borne  out  by  the  fact  of  their  entire  absence  from  the 
food  which  nature  provides  for  young  animals.  Healthy 
milk  is  absolutely  sterile. 

As  it  is  at  present  impracticable  to  obtain  water,  uni- 
formly at  least,  free  from  microbes,  it  is  desirable  to  adopt 
some  standard  of  bacterial  purity  ;  and  100  microbes  per 
cubic  centimetre  has  been  fixed  upon  by  Dr.  Koch  and 
myself  as  the  maximum  number  allowable  in  potable  water. 
This  standard  is  very  rarely  infringed  by  the  London 
Water  Companies,  whilst  I  have  every  reason  to  hope  that, 


THE  WATER  SUPPLY  OF  LONDON.  175 

in  the  near  future,  now  that  special  attention  is  directed  to 
bacterial  filtration,  it  will  not  be  approached  within  50  per 
cent.  This  hope  is  based  not  only  upon  my  own  observations, 
but  also  upon  the  exhaustive  and  exceedingly  important 
investigations  carried  out  at  the  Lawrence  Experiment 
Station  by  the  State  Board  of  Health  of  Massachussetts, 
under  the  direction  of  Mr.  George  W.  Fuller,  the  official 
biologist  to  the  Board. 

More  than  six  years  have  already  been  spent  in  the  prose- 
cution of  these  American  experiments,  and  many  thousands 
of  samples  of  water  have  been  submitted  to  bacterial  cultiva- 
tion. The  Massachussetts  experimental  filters  are  worked  at 
rates  up  to  3,000,000  gallons  per  acre  daily,  which  renders 
the  results  available  for  application  to  public  water  supplies  ; 
indeed  none  of  the  water  delivered  in  London  is  filtered  at 
so  rapid  a  rate  as  this.  It  was  found  that  at  these  rates  all 
the  disease-producing  germs,  which  were  intentionally  and 
in  large  numbers  added  to  the  unfiltered  water,  were 
substantially  removed.  The  filters  were  so  constructed 
and  arranged  as  to  allow  direct  comparison  of  the  bacterial 
purification  of  water  under  different  rates  of  filtration,  with 
sand  of  different  degrees  of  fineness,  with  different  depths 
of  the  same  sand,  and  with  intermittent  and  continuous 
filtration. 

The  actual  efficiency  of  these  filters  was  also  tested  by 
the  application  of  the  bacillus  of  typhoid  fever.  Very  large 
numbers  of  these  bacilli  and  of  other  species  were  applied 
in  single  doses  to  the  several  filters  at  different  times,  and 
the  effluent  was  examined  four  times  daily  for  several  days 
afterwards.  The  results  so  obtained  give  a  thoroughly 
trustworthy  test  of  the  degree  of  bacterial  purification 
effected  by  each  of  the  experimental  filters,  and  these  are 
the  data  which  have  been  largely  used  by  the  Mas- 
sachussetts State  Board  of  Health  in  deducing  the  rules 
which  they  consider  ought  to  be  observed  in  water  filtration. 

Among  the  subjects  investigated  by  means  of  these 
experimental  filters  were  : — 

1.   The  effect,  upon  bacterial  purification,  of  the  rate  of 
filtration. 


176  SCIENCE  PROGRESS. 

2.  The  effect  of  size    of  sand    grains  upon    bacterial 

purification. 

3.  The    effect    of   depth    of    material    upon    bacterial 

purification. 

4.  The   effect  of  scraping   the    filters    upon    bacterial 

purification. 
Time  does  not  permit  of  my  giving  the  answers  to  these 
questions  in  detail ;  but  they  may  be  summarised  as  follows : — 

1.  The  rate  of  filtration  between  500,000  and  3,000,000 
gallons  per  acre  per  day  exercises  practically  no  effect  on 
the  bacterial  purity  of  the  filtered  water.  It  is  worthy  of 
note  that  the  rates  of  filtration  practised  by  the  several 
Water  Companies  drawing  their  supplies  from  the  Thames 
and  Lea  are  as  follows:  Chelsea  Company,  1,830,000; 
West  Middlesex,  1,359,072  ;  Southwark  Company,  1,568, 160; 
Grand  Junction  Company,  1,986,336;  Lambeth  Company, 
1,477,688;  New  River  Company,  1,881,792;  and  East 
London  Company,  1,393,920.  Hence  not  one  of  the 
London  Companies  filters  at  the  rate  of  2,000,000  gallons 
per  acre  per  day  ;  at  which  rate  in  the  Massachussett's 
filters  99*9  per  cent,  of  the  microbes  present  in  the  raw 
water  were  removed. 

2.  The  effect  of  size  of  sand  grains  was  found  to  be  very 
considerable  ;  and,  in  confirmation,  I  find  that  by  the  use  of 
a  finer  sand  than  that  employed  by  the  Chelsea  Company, 
the  West  Middlesex  Company  is  able,  with  much  less  stor- 
age, to  attain  an  equal  degree  of  bacterial  efficiency. 

3.  The  depth  of  sand,  between  the  limits  of  one  and  five 
feet,  exercises  no  practical  effect  on  bacterial  purity  when 
the  rate  of  filtration  is  kept  within  the  limits  just  specified. 
And  this  result  is  quite  borne  out  by  my  own  experience 
gained  in  the  bacterioscopic  examination  of  the  filtered 
waters  of  the  seven  Companies  supplying  the  Metropolis 
from  rivers.  Thus  the  New  River  Company,  with  i*8  feet 
of  sand  on  the  filters,  compares  favourably  with  the  Chelsea 
Company,  the  sand  on  whose  filters  is  more  than  twice  that 
depth. 

Placed  in  the  order  of  thickness  of  sand  on  their  filters, 
the   Metropolitan   Companies    range    as  follows :    Chelsea, 


THE  WATER  SUPPLY  OF  LONDON.  177 

Lambeth,  West  Middlesex,  Southwark,  East  London, 
Grand  Junction,  and  New  River.  Placed  in  the  order  of 
efficient  filtration  they  range  as  follows  :  Chelsea  and  West 
Middlesex  equal,  New  River,  Lambeth,  East  London, 
Southwark,  and  Grand  Junction. 

4.  When  there  is  such  an  accumulation  of  deposit  on 
the  surface  of  a  sand  filter  that,  for  practical  purposes, 
sufficient  water  cannot  be  made  to  pass  through  it,  the 
surface  of  the  filter  has  to  be  scraped  ;  that  is  to  say,  the 
mud  and  about  half  an  inch  of  the  sand  are  removed  from 
the  surface.  After  this  operation,  there  is  sometimes  an 
increase  in  the  number  of  bacteria  in  the  filtered  water,  and 
it  was  noticed  that  the  increase  was  greater  in  shallow  than 
in  deep  filters  and  with  high  than  with  low  rates  of  filtration; 
and  there  is  no  doubt  that  the  effect  of  scraping  is  con- 
siderably magnified  when  coarser  descriptions  of  sand  are 
employed,  as  in  the  case  of  the  filters  of  the  London  Water 
Companies.  I  should  like,  therefore,  to  impress  upon  the 
engineers  of  these  Companies  the  desirability  of  using  finer 
sands  than  are  at  present  employed. 


INFLUENCE  OF  THE  BACTERIAL  CONDITION  OF  THE  RAW 
RIVER  WATER  UPON  THAT  OF  THE  FILTERED  EF- 
FLUENT. 

I  have  found  that  the  number  of  bacteria  in  a  given 
volume  of  filtered  water  is  to  a  considerable  extent  in- 
fluenced by  the  number  contained  in  the  raw  water  supplying 
the  filter  ;  and  from  this  point  of  view,  therefore,  the  bacterial 
condition  of  the  raw  river  water  used  in  the  Metropolis  is  of 
no  inconsiderable  importance. 

Since  May,  1892,  I  have  made  monthly  determina- 
tions of  the  number  of  microbes  capable  of  developing 
on  a  gelatine  plate  in  a  given  volume  of  raw  Thames  water 
collected  at  the  intakes  of  the  Metropolitan  Water  Companies 
at  Hampton  ;  and  the  number  has  varied  during  this  time 
between  631  and  56,630  per  cubic  centimetre,  the  highest 
numbers  having,  as  a  rule,  been  found  in  winter  or  when 


178 


SCIENCE  PROGRESS. 


the    temperature    of  the   water    was   low,   and    the  lowest 
in  summer  or  when  the  temperature  was  high. 

Now,  besides  temperature,  there  are  two  other  conditions 
to  either  of  which  this  difference  may  be  attributed,  viz.y 
sunshine  and  rainfall,  and  I  have  endeavoured  by  a  series 
of  graphic  representations  to  disentangle  these  possible 
influences  from  each  other  by  placing  the  results  of  the 
microbe  determinations  in  juxtaposition  with  (i)  the  tem- 
perature of  the  water  at  the  time  the  samples  were  taken  ; 


^   3b 

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No.  7. 

(2)  the  number  of  hours  of  sunshine  on  the  day  and  up  to 
the  hour  when  each  sample  was  drawn  and  on  the  two 
preceding  days,  and  (3)  the  flow  of  the  Thames  over 
Teddington  Weir  on  the  same  day  expressed  in  millions 
of  gallons  per  twenty-four  hours.  Although  the  graphic 
representations  were  confined  to  the  Thames,  the  conditions 
affecting  bacterial  life  in  this  river  are  doubtless  equally 
potent  in  other  rivers  and  streams. 

The  samples  for  microbe  cultivation  were  collected  at 


THE  WATER  SUPPLY  OF  LONDON. 


179 


about  nine  inches  below  the  surface  of  the  water  in  partially 
exhausted  and  sealed  tubes,  the  ends  of  which,  when  the 
tubes  were  lowered  to  the  required  depth,  were  broken  off 
by  an  ingenious  contrivance  devised  by  my  Assistant,  Mr. 
Burgess.  On  being  withdrawn  from  the  river  the  tubes 
were  immediately  hermetically  sealed  and  packed  in  ice  for 
conveyance  to  my  laboratory,  where  the  cultivation  was 
always  commenced  within  four  hours  of  the  time  of  collection. 


Ktp 

dun  JuJi 

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Feb.  MrMprl  %  dun  My  A  ub  Sep  Oct  Hot  Dec  Jail 

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No.  8. 


For  the  records  of  sunshine,  I  am  indebted  to  the 
kindness  of  Mr.  James  B.  Jordan  of  Staines  ;  and  for 
gaugings  of  the  Thames  at  Teddington  Weir  to  Mr.  C.  J. 
More,  the  engineer  to  the  Thames  Conservancy  Board. 

The  graphic  representation  of  these  collateral  observa- 
tions affords  definite  evidence  as  to  which  of  the  three 
conditions — temperature,  sunshine,  and  Mow  of  the  river — 
has  the  predominant  influence  upon  bacterial  life  in  the 
water.     The  first  diagram  (No.  7)  compares  the  number  of 

13 


i8o 


SCIENCE  PROGRESS. 


microbes  per  cubic  centimetre  with  the  temperature  at  the 
time  the  sample  was  taken.  The  horizontal  lines  express 
the  numbers  of  microbes  and  the  temperature,  while  the 
vertical  lines  denote  the  months  when  the  samples  were 
taken.  For  obvious  reasons  the  horizontal  lines  express- 
ing the  numbers  of  microbes  and  temperatures  are  num- 
bered in  opposite  directions. 

The  diagram  shows  that  although  coincidences  between 
a  high  number  of  microbes  and  a  low  temperature  are  not 


is 

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No.  9. 


wanting,  some  other  condition  entirely  masks  the  effect,  if 
any,  of  temperature. 

The  next  diagram  (No.  8)  institutes  the  comparison 
between  the  number  of  microbes  and  the  hours  of  sun- 
shine to  which  the  water  has  been  exposed.  The  diagram 
is  constructed  on  the  same  lines  as  the  first. 

It  is  here  seen  that,  as  in  the  case  of  temperature, 
there  is  some  other  condition  which  entirely  overbears  the 
influence  of  sunlight  in  the  destruction  of  microbes  in  the 


THE  WATER  SUPPLY  OF  LONDON.  181 

river  water.  This  condition  is  the  amount  of  rainfall  higher 
up  the  river,  or,  in  other  words,  the  volume  of  water  flowing 
along  the  river  bed,  as  is  seen  from  the  comparison  repre- 
sented in  the  next  diagram  (No.  9). 

This  diagram  shows  very  conclusively  that  the  volume 
of  water  flowing  in  the  Thames  is  the  paramount  influence 
determining  the  number  of  microbes.  It  compares  the 
volume  of  water  in  the  river  gauged  at  Teddington  Weir 
with  the  number  of  microbes  found  in  the  raw  Thames 
water  at  Hampton  on  the  same  day.  In  this  diagram,  the 
numbers  representing  the  flow  of  the  river  in  millions  of 
gallons  per  day  and  the  number  of  microbes  per  cubic 
centimetre  in  the  water  both  run  from  the  bottom  of  the 
diagram  upwards. 

Comparing  the  curves  in  the  diagram  it  is  seen  that, 
with  very  few  exceptions,  a  remarkably  close  relation  is 
maintained  between  them. 

The  only  exception  of  any  importance  to  the  rule  that 
the  number  of  microbes  varies  directly  with  the  flow  of 
the  river,  occurring  during  the  thirty-two  months  through 
which  these  observations  were  continued,  happened  in 
November,  1892,  when  the  flow  increased  from  501  mil- 
lions of  gallons  in  October  to  1845  millions  in  November, 
whilst  the  microbes  actually  diminished  in  number  from 
2216  to  1868  per  cubic  centimetre.  Neither  the  sunshine 
nor  the  temperature  records  of  these  two  months,  however, 
afford  any  explanation  of  this  anomalous  result,  for  there 
was  a  good  deal  of  sunshine  in  October  before  the  collection 
of  the  sample  and  the  temperature  was  higher,  whilst  in 
November  no  ray  of  sunshine  reached  the  Thames  during 
the  three  days  preceding  the  taking  of  the  sample  and  the 
temperature  was  nearly  40  C.  lower  than  in  the  preceding 
month.  I  have  ascertained,  however,  that  the  Thames 
basin  had  been  twice  very  thoroughly  washed  out  by  heavy 
floods  before  the  time  when  the  November  sample  was 
taken,  and  this  affords  a  satisfactory  explanation  of  the 
anomalous  result  yielded  by  this  sample. 

These  comparisons  demonstrate  that  the  number  of 
microbes  in  Thames  water  depends  directly  upon  the  rate 


182 


SCIENCE  PROGRESS. 


of  flow  of  the  river,  or,  in  other  words,  on  the  rainfall,  and 
but  slightly,  if  at  all,  upon  either  the  presence  or  absence  of 
sunshine  or  a  high  or  low  temperature  ;  and  they  are  con- 
firmed by  the  continuation  of  these  observations  during  the 
year  1895  exhibits  in  diagram  No.  10. 

With  regard  to  the  effect  of  sunshine  upon  bacterial 
life,  the  interesting  observations  of  Dr.  Marshall  Ward 
leave  no  doubt  that  sunlight  is  a  powerful  germicide  ;  still 
it  is  obvious  that  its  potency  in  this  respect  must  be  greatly 
diminished,  if  not  entirely  annulled,  when  the  solar  rays 
have    passed   through    a  stratum   of   water  of  even    com- 

MICROBES  and  FLOW  of  THAMES 


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No.  10. 


paratively  small  thickness  before  they  reach  the  living 
organisms.  By  a  series  of  ingeniously  contrived  experi- 
ments, Mr.  Burgess  has  demonstrated  the  correctness  of 
this  view. 

A  sterile  bottle  about  half  filled  with  Thames  water  was 
violently  agitated  for  five  minutes  to  insure  equal  distribu- 
tion of  the  organisms.  Immediately  afterwards  a  number 
of  sterile  glass  tubes  were  partially  filled  with  this  water 
and  sealed  hermetically.  Three  of  these  tubes  were 
immediately  packed  in  ice,  and  the  remainder  were  attached 
in  duplicate  at  definite  distances  apart  to  a  light  wire  frame 
which   was  then  suspended  vertically  in    the   river.     The 


THE  WATER  SUPPLY  OF  LONDON.  183 

experiments  were  made  near  the  Grand  Junction  Company's 
Intake  at  a  place  favourable  for  the  sun's  rays  to  fall  on  the 
river  without  any  obstruction. 

The  river  was  at  the  time  in  a  very  clear  condition  and 
contained  but  little  suspended  matter  ;  whilst  the  day  was 
fine,  although  clouds  obscured  the  sun  occasionally.  The 
tubes  were  exposed  to  light  in  the  river  for  four  and  a  half 
hours — from  ICV30  a.m.  to  3  r.M.  on  15th  May,  1895.  At 
the  end  of  this  time  the  tubes  were  packed  in  ice  for  trans- 
port to  my  laboratory,  where  the  cultivation  was  started 
immediately.  The  colonies  were  counted  on  the  fourth  day 
and  yielded  the  results  given  in  the  table  : — 

No.  of  Colonies 
per  c.c. 
Thames  water  packed  in  ice  immediately  after  collection  -     2127 
Thames  water  after  exposure  to  sunlight  for  4^  hours  at 

surface  of  river       -------     1140 

Thames  water  after  exposure  to  sunlight  for  4^  hours  at 

6  in.  below  surface  of  river      -----     i^o 

Thames  water  after   exposure  to  sunlight  for  4^  hours  at 

1  ft.  below  surface  of  river      -         -         -         -         -     2150 
Thames  water  after  exposure   to  sunlight  for  4J  hours  at 

2  ft.  below  surface  of  river       -----     2430 
Thames  water  after  exposure  to  sunlight  for  4!  hours  at 

3  ft.  below  surface  of  river       -----     2440 

These  experiments  show  that,  on  15th  May  the 
germicidal  effect  of  sunlight  on  Thames  microbes  was  nil 
at  depths  of  one  foot  and  upwards  from  the  surface  of  the 
water.  It  cannot,  therefore,  excite  surprise,  that  the  effect 
of  sunshine  upon  bacterial  life  in  the  great  mass  of  Thames 
water  should  be  nearly,  if  not  quite,  imperceptible.  It  is 
thus  ascertained  that  sunlight  can  only  kill  the  germs,  or 
microbes,  near  the  surface  of  the  water,  whilst  those  at  any 
depth,  for  the  most  part,  escape  destruction. 

On  the  other  hand  the  enormous  effect  of  floods  in 
augmenting  the  number  of  microbes  can  hardly  surprise  us, 
for  when  a  great  body  of  water  has  flowed  over  the  banks 
of  the  river,  which  are  at  other  times  dry  and  exposed,  it 
carries  along  with  it  countless  impurities — an  effect  common 
both  to  the  main  stream  and  its  tributaries.     The  Thames 


184  SCIENCE  PROGRESS. 

basin   is  as    it  were,  on    every   such    occasion,  thoroughly- 
washed  out,  and  it  is  only  to  be  expected  that  the  number 
of  microbes  in  the  water  should  be  enormously  increased  as 
is  found  to  be  the  case. 
Now  with  respect  to 

THE  WATER  SUPPLY  OF  THE  FUTURE. 

In  view  of  the  rapid  increase  of  the  population  of  Lon- 
don, fears  have  from  time  to  time  been  entertained  that  the 
water  supply  from  the  Thames  basin,  that  is  to  say  from 
the  rivers  Thames  and  Lea,  supplemented  by  water  from 
springs  and  deep  wells  within  the  basin  itself,  would  soon 
be  insufficient  in  quantity ;  whilst  the  quality  of  the 
water  taken  from  the  river  has,  up  to  a  comparatively 
recent  date,  been  considered  unsatisfactory.  On  these 
grounds  various  schemes  have,  from  time  to  time,  been 
brought  forward  for  the  supply  of  the  Metropolis  from 
other  river  basins — from  the  Wye,  the  Severn,  the  river 
basins  of  North  Wales,  and  of  the  Lake  Districts  of 
Cumberland  and  Westmoreland. 

It  is  worthy  of  note,  however,  that  all  the  Royal  Com- 
missions have  arrived  tinanimously  at  the  conclusion 
that  the  quantity  of  water  obtainable  from  the  Thames 
basin  is  so  ample  as  to  render  the  necessity  of  going  else- 
where a  very  remote  contingency. 

I  shall  now  endeavour  to  put,  very  shortly  before  you 
a  few  facts  which,  in  my  opinion,  prove  that,  both  as 
regards  quantity  and  quality,  the  Thames  basin  will  for  a  very 
long  time  to  come  afford  an  abundant  supply  for  the  Metro- 
polis. There  is  indeed  no  river  basin  in  Great  Britain 
which  affords  such  an  abundant  supply  of  excellent  water 
as  that  available  in  the  Thames  basin. 

Besides  that  which  flows  directly  into  the  rivers,  this 
water  is  contained  in  the  Chalk,  Oolite,  and  Lower  Green- 
sand,  which  are  the  best  water  bearing  strata  in  the 
kingdom.  From  these  rocks  it  issues  in  copious  springs 
of  unsurpassed  organic  purity.  I  have  personally  inspected 
every  spring  of  importance  in  the  Thames  basin  and  have 


THE  WATER  SUPPLY  OF  LONDON. 


185 


analysed  samples  of  the  water.     The  results,  in  a  very  con- 
densed form,  are  recorded  in  the  annexed  Table.     Twenty- 


SPRING  AND  DEEP-WELL  WATERS    IN    THE  THAMES 

BASIN. 


Results  of  Analysis  in 
Parts  per  100,000. 

Oolite. 

Average  of 21 

Samples. 

Lower 

Greensand. 

Average  of  5 

Samples. 

Chalk. 

Springs. 

Average  of  8 

Samples. 

Wells. 

Average  of  36 

Samples. 

Total  Saline  Matters  - 
Organic  Carbon      -     - 
Organic  Nitrogen  -     - 
Hardness  before  boiling 

after 

27*34 

•°35 
"OI2 

22-5 

5-5 

18-25 
•032 
•006 

IO-5 
3-6 

3°'M 
'041 
•010 

25'3 
4*9 

37-45 

•052 

•019 

28-0 

6-5 

one  samples  of  Oolitic  spring-  water  were  analysed,  and 
every  one  of  these  was  of  even  greater  organic  purity 
than  the  water  delivered  by  the  Kent  Company,  which  I 
have  always  regarded  as  the  standard  of  organic  purity  to  be 
aimed  at  in  all  other  Water  Works. 

Five  springs  issuing  from  the  Lower  Greensand  were 
examined  ;  and  again,  every  one  of  these  was  of  even 
greater  purity,  organically,  than  the  Kent  Company's 
water ;  whilst  they  were,  on  the  average,  only  one-third  as 
hard.  Forty-six  samples  of  water  from  the  Chalk  were 
chemically  examined,  and  these  also  contained  but  the 
merest  traces  of  organic  matter. 

All  these  samples  from  the  Chalk  were  derived  from 
sources  where  the  water-bearing-  stratum  is  free  from  a 
covering  of  London  clay  ;  but,  as  soon  as  the  Chalk  dips 
beneath  the  London  Tertiary  Sands  and  clay,  the  quality  of 
the  water  undergoes  a  remarkable  alteration.  The  total 
solids  in  solution  are  greatly  increased  in  amount,  whilst 
the  hardness  is  much  mitigated,  owing  to  the  replacement 
of  bicarbonate  of  lime  by  bicarbonate  of  soda.  These 
waters  are  also  of  high  organic  purity  ;  but,  as  the  quantity 
is  very  limited,  it   is   useless   to  dwell   upon   them.     They 


186  SCIENCE  PROGRESS. 

supply  the  Trafalgar  Square  fountains  and  the  London 
breweries,  and  we  can  well  afford  to  leave  them  to  be  con- 
verted into  beer.  For  dietetic  purposes  there  is  no  better 
water  in  the  kingdom  than  the  underground  water  of  the 
Thames  basin.  For  sentimental  reasons  I  should  like  to 
see  it  conveyed  to  the  works  of  the  various  companies  in 
special  conduits  ;  but  we  have  seen  that,  on  hygienic 
grounds,  it  may  safely  be  allowed  to  flow  down  the  bed  of 
the  Thames  if  it  be  afterwards  efficiently  filtered. 

So  much  for  quality,  now  as  to  quantity  ;  the  basins  of 
the  Thames  and  Lea  include  an  area  of  upwards  of  5000 
square  miles.  Of  this  rather  more  than  one  half  (including 
the  Oolitic,  Cretaceous,  and  portions  of  the  Tertiary  Forma- 
tions) is  covered  by  a  porous  soil  upon  a  permeable  water 
bearing  stratum.  The  remainder  is  occupied  by  the 
Oxford,  Kimmeridge,  Gault,  and  London  Clays ;  being 
thus  covered  by  a  clay  soil  upon  a  stiff  and  impervious 
subsoil. 

The  annual  rainfall  of  the  district  is  estimated  at  an 
average  of  twenty-eight  inches.  The  rivulets  and  streams 
of  the  Thames  basin  are  formed  and  pursue  their  course  on 
clay  land.  There  are  no  streams  on  the  Chalk.  That 
which  falls  upon  this  porous  stratum  and  does  not  evaporate 
sinks,  mostly  where  it  alights,  and  heaps  itself  up  in  the 
water-bearing  stratum  below,  until  the  latter  can  hold  no 
more.  The  water  then  escapes  as  springs  at  the  lowest 
available  points. 

Innumerable  examples  of  these  springs  occur  all  round 
the  edge  of  the  Thames  basin,  and  at  various  points  within 
it.  Thus  from  the  Chalk  they  are  ejected  at  the  lip  of  the 
Gault ;  and  in  the  Oolitic  area  by  the  Fuller's  Earth  below 
it,  or  by  the  Oxford  Clay,  geologically,  above  it. 

According  to  the  guagings  of  the  engineer  of  the 
Thames  Conservancy  Board  there  passed  over  Teddington 
Weir,  in  1892,  387,000  millions  of  gallons,  equal  to  an 
average  flow  of  1060  millions  of  gallons  daily.  In  the 
following  year,  1893,  their  passed  over  Teddington  Weir 
an  aggregate  of  324,227  millions  of  gallons,  or  a  daily 
average  of  888  millions,  the  average  for  the  two  years  being 


THE  WATER  SUPPLY  OF  LONDON.  187 

974  millions  of  gallons,  and  this  number  does  not  in- 
clude the  1 20  millions  daily  abstracted  by  the  five  London 
Water  Companies  who  draw  their  supplies  from  the 
Thames. 

Thus,  in  round  numbers,  we  may  say  that  after  the 
present  wants  of  London  have  been  supplied  from  this 
river,  there  is  a  daily  average  of  nearly  1000  millions  of 
gallons  to  spare.  Surely  it  is  not  too  violent  an  assumption 
to  make  that  the  enterprising  engineers  of  this  country  can 
find  the  means  of  abstracting  and  storing  for  the  necessary 
time  one-fourth  of  this  volume. 

As  regards  the  quality  of  this  stored  water,  all  my 
examinations,  of  the  effect  of  storage  upon  the  chemical  and 
especially  upon  the  bacterial  quality,  point  to  the  conclusion 
that  it  would  be  excellent.  Indeed  the  bacterial  improve- 
ment of  river  water  by  storage  for  even  a  few  days  is 
beyond  all  expectation.  Thus  the  storage  of  Thames  water 
by  the  Chelsea  Company  for  only  thirteen  days  reduces 
the  number  of  microbes  to  one-fifth  the  original  amount, 
and  the  storage  of  the  river  Lea  water  for  fifteen  days, 
by  the  East  London  Company,  reduces  the  number  on  the 
average  from  9240  to  i860  per  cubic  centimetre  or  to  one- 
fifth  ;  and  lastly,  the  water  of  the  New  River  Cut,  con- 
taining on  the  average  4270  microbes  per  cubic  centimetre 
contains,  after  storage  for  less  than  five  days,  only  18 10, 
the  reduction  here  being  not  so  great,  partly  on  account 
of  the  shorter  storage,  but  chiefly  because  the  New  River 
Cut  above  the  point  at  which  the  samples  were  taken,  is 
itself  a  storage  reservoir  containing  many  days'  supply  after 
filtration.  Indeed  quietness  in  a  subsidence  reservoir  is, 
very  curiously,  far  more  fatal  to  bacterial  life  than  the  most 
violent  agitation  in  contact  with  atmospheric  air ;  for  the 
microbes  which  are  sent  into  the  river  above  the  falls  of 
Niagara,  by  the  City  of  Buffalo,  seem  to  take  little  or  no 
harm  from  that  tremendous  leap  and  turmoil  of  waters, 
whilst  they  subsequently,  very  soon,  almost  entirely  dis- 
appear in  Lake  Ontario. 

It  is  not,  therefore,  too  much  to  expect  that  storage  for, 
say    a   couple    of  months,    would    reduce    the    number  of 


188  SCIENCE  PROGRESS. 

microbes  in  the  Thames  flood  water  down  to  nearly  the 
minimum  ever  found  in  that  river  in  dry  weather,  whilst, 
by  avoiding  the  first  rush  of  each  flood,  a  good  chemical 
quality  could  also  be  secured. 

There  is,  therefore,  I  think,  a  fair  prospect  that  the 
quantity  of  water  derivable  from  the  Thames  at  Hampton 
could  be  increased  from  its  present  amount  (120  millions  of 
gallons  per  diem)  to  370  millions. 

Again,  in  the  river  Lea,  although  here  the  necessary 
data  for  exact  calculations  are  wanting,  it  may  be  assumed 
that  the  present  supply  of  54  millions  of  gallons  could 
be  increased  by  the  storage  of  flood  water  to  100 
millions  per  day.  To  these  volumes  must  be  added  the 
amount  of  deep-well  water  which  is  attainable  from  those 
parts  of  the  Thames  basin  which  lie  below  Teddington  Lock, 
and  in  the  Lea  basin  beloiv  Lea  Bridge,  and  which  was 
estimated  by  the  last  Royal  Commission  at  rather  more 
than  67J  millions  of  gallons. 

Thus  we  get  the  grand  total  of  53735-  millions  of 
gallons  of  excellent  water  obtainable  within  the  Thames 
basin,  the  quality  of  which  can  be  gradually  improved,  if  it 
be  considered  necessary,  by  pumping  from  the  water  bear- 
ing strata  above  Teddington  and  Lea  Bridge  respectively, 
instead  of  taking  the  total  supply  from  the  open  rivers 
above  these  points.  Such  a  volume  of  water  would  scarcely 
be  required  for  the  supply  of  the  whole  water  area  of  Lon- 
don at  the  end  of  fifty  years  from  the  present  time,  even 
supposing  the  population  to  go  on  increasing  at  the  same 
rate  as  it  did  in  the  decade  1881-91,  which  is  an  assumption 
scarcely  likely  to  be  verified. 

In  conclusion,  I  have  shown  that  the  Thames  basin  can 
furnish  an  ample  supply  for  fifty  or  more  years  to  come, 
whilst  the  quality  of  the  spring  and  deep-well  waters  and  of 
the  filtered  river  water  would  be  unimpeachable.  To  secure 
these  benefits  for  the  future,  storage  must  be  gradually  pro- 
vided for  1 1,500  millions  of  gallons  of  flood  water  judiciously 
selected  in  the  Thames  Valley,  and  a  proportionate  volume 
in  the  basin  of  the  Lea  ;  whilst  filtration  must  be  carried  to 
its  utmost  perfection   by  the  use  of  finer  sand   than   is  at 


THE  WATER  SUPPLY  OF  LONDON.  189 

present  employed,  and  by  the  maintenance  of  a  uniform  rate 
during  the  twenty-four  hours. 

There  is  nothing  heroic  in  laying  pipes  along  the  banks 
of  the  Thames,  or  even  making  reservoirs  in  the  Thames 
basin.  They  do  not  appeal  to  the  imagination  like  that 
colossal  work,  the  bringing  of  water  to  Birmingham  from 
the  mountains  of  Wales,  and  there  is  little  in  such  a  scheme 
to  recommend  it  to  the  minds  of  the  enterprising  engineers 
of  to-day.  Nevertheless,  by  means  of  storage,  by  utilising 
springs,  by  sinking  deep  wells,  and  by  such  comparatively 
simple  means,  we  have,  in  my  opinion,  every  reason  to  con- 
gratulate ourselves  that  for  half  a  century  at  least  we  have 
at  our  dooi's,  so  to  speak,  an  ample  supply  of  water  which  for 
palatability,  wholesomeness,  and  general  excellence  will  not 
be  surpassed  by  any  supply  in  the  world. 

E.   Frankland. 


SOME     RECENT     MEMOIRS     UPON 
OLIGOCH^TA. 

THE  literature  relating  to  this  group  of  worms  is 
summed  up  in  my  Monograph  of  the  Oligochceta 
lately  issued  by  the  Clarendon  Press  ;  but  so  energetic  are 
the  unfortunately  somewhat  few  workers  in  this  particular 
subject  that  new  facts  have  gone  on  accumulating  with  some 
rapidity  since  the  publication  of  that  work.  It  is  my 
intention  in  the  present  article  to  offer  the  reader  a  re'sume 
of  this  latest  work  with,  naturally,  some  references  to  what 
has  gone  before. 

It  is  agreed  by  all  those  who  are  acquainted  with  the 
terrestrial  Oligochaeta  that  their  peculiar  mode  of  life,  their 
susceptibility  to  sea  water,  and  the  comparatively  few 
chances  of  dispersal  enjoyed  by  them,  render  their  distribu- 
tion highly  important  in  estimating  the  relations  between 
land  masses  now  and  in  the  past.  This  has  an  especial 
bearing  upon  the  theory  of  the  former  northward  extension 
of  the  Antarctic  Continent,  a  matter  upon  which  much  has 
been  written  lately.  To  deal  adequately  with  this  large 
question  would  of  course  demand  more  space  than  can  be 
allowed  me.  I  shall  content  myself  with  referring  solely  to 
the  evidence  which  is  forthcoming  from  the  study  of  earth- 
worms. Fortunately  we  are  in  possession  of  a  considerable 
amount  of  information  about  the  terrestrial  Olioochaeta  of 
New  Zealand  and  Patagonia  ;  the  former  country  indeed 
must  be  regarded  as  being  better  known  perhaps  than  any 
quarter  of  the  globe,  excepting  of  course  Europe.  The 
extensive  collections  lately  made  by  Dr.  Michaelsen  in 
South  America  have  added  largely  to  the  number  of  species 
brought  back  by  his  predecessors.  It  results  from  an 
examination  of  the  species  found  in  the  two  countries  that 
in  both  of  them  the  prevailing  types  belong  to  the  genera 
Acanthodrilus  and  Microscolex,  particularly  the  former.  Of 
the  thirty-two  indigenous  species  at  present  known  from 
Patagonia  and  the  more  southern  parts  of  the  South  Ameri- 


SOME  RECENT  MEMOIRS  UPON  OLIGOCH/ETA.     191 

can  Continent,  twenty  are  members  of  the  genus  Acantho- 
drilus, eleven  are  Microscolex  and  one  is  a  PericJiesta.  Besides 
these  are  a  few  obviously  imported  Lumbricus  and 
Allolobophora  from  Europe  or  North  America.  I  say 
obviously  imported  because  these  worms  are  only  found  in 
cultivated  ground  and  near  the  coast  ;  as  civilisation  is  left 
behind  these  species  decrease  and  are  replaced  by  the 
truly  indigenous  species.  Among  the  twenty  species  of 
Acanthodrilus  are  included  two  or  three  which  occur  in  the 
Falkland  Islands  and  in  South  Georgia.  Turning  to  New 
Zealand  we  find  that  out  of  twenty  indigenous  species  nine 
are  Acanthodrilus,  six  belong  to  the  closely  allied  genera 
Octochcehis,  Deinodrilus,  and  Plagiochcsta,  three  are  Micro- 
scolex, while  the  two  remaining  are  a  Perichceta  and  a 
Megascolides,  two  genera  which  are  eminently  characteristic 
of  the  adjoining  continent  of  Australia.  Between  New 
Zealand  and  South  America  is  a  long  stretch  of  ocean, 
sparsely  scattered  over  which  are  islands  of  volcanic  origin. 
From  three  of  these  islands  earthworms  have  been  collected. 
In  Kerguelen  and  Marion  Island  is  a  species  of  Acantho- 
drilus peculiar  to  those  islands,  and  I  have  lately  received, 
and  am  describing  in  the  forthcoming  June  number  of  the 
Proceedings  of  the  Zoological  Society,  a  second  species  of 
that  genus  from  Macquarie  Island.  The  significance  of 
these  facts  will  be  more  apparent  when  we  consider  how 
far  the  genera  that  have  been  referred  to  in  the  fore- 
going are  distributed  outside  of  this  antarctic  area.  Micro- 
scolex is  found  in  many  parts  of  central  and  the  warmer 
western  regions  of  North  America  ;  it  has  been  met  with 
also  in  Europe,  Algeria  and  Teneriffe.  Acanthodrilus 
occurs  in  Australia  where  it  is  represented  by  three  species, 
all  of  which  however  inhabit  the  eastern  half  of  the  island 
continent,  that  part  in  fact  which  is  nearest  to  New 
Zealand  ;  Acanthodrilus  has  one  species  in  Natal,  one  in 
New  Caledonia  and  two  in  North  America. 

We  have  evidently  therefore  a  fauna  of  earthworms 
peculiar  to  the  antarctic  region,  into  which  more  northern 
forms  have  been  able  to  make  but  slight  inroads  and  from 
which  but  few  stragglers  have  wandered. 


i92  SCIENCE  PROGRESS. 

As  to  other  distributional  facts  and  theories,  it  is 
probable  that  I  have  underestimated  in  my  Monograph  the 
distinctness  of  the  Palaearctic  and  the  Nearctic  regions  of 
Mr.  Sclater.  I  was  disposed  to  unite  them  into  one  Hol- 
arctic  as  Professor  Newton  has  called  it.  Further  investi- 
gations have  tended  to  emphasise  the  justice  of  separating 
these  two  regions.  This  evidence  has  been  mainly  collected 
by  the  industry  of  Dr.  Gustav  Eisen,  of  San  Francisco  ; 
but  others  whose  names  and  memoirs  will  be  found  quoted 
in  the  list  of  literature  at  the  end  of  this  article  have  added 
details  of  importance.  The  North  American  continent  is 
inhabited  by  a  fair  number  of  peculiar  genera,  of  which 
Diplocardia,  originally  described  some  years  since  by 
Garman,  has  four  species  (partly  referred  to  the  undoubtedly 
synonymous  genus  Geodrilus) ;  there  are  also  peculiar  to 
this  region  Phoenicodrilus,  nearly  related  to  the  central 
and  South  America  Ocuerodrilus,  and  Sparganophilus ;  of 
this  latter  genus  the  original  species  was  found  by 
Benham  in  the  Thames  ;  but  as  there  are  half  a  dozen 
American  species  it  seems  likely  that  its  occurrence  in 
England  is  a  case  of  importation.  Bimastos  is  a  genus 
perhaps  justly  separable  from  Allolobophora,  from  which  it 
chiefly  differs  in  the  large  size  (for  a  Lumbricid)  of  the 
glandular  sac  in  which  the  efferent  male  ducts  terminate. 
Besides  these  peculiar  genera  are  a  few  species  of  the 
Central  and  South  American  genera  Ocuerodrilus  and 
Kerria,  and  of  the  almost  world-wide  Benhamia.  Aleodrilus 
is  an  Acanthodrilid  that  Eisen  is  disposed  to  separate  from 
Diplocardia ;  two  species  of  Acanthodrilus  complete  the 
list  of  non-European  inhabitants  of  the  North  American 
Continent.  But  in  addition  to  these  are  a  number  of  Allolo- 
bophora and  Lumbricus — the  characteristic  forms  ol  the 
Palaearctic  region — two  or  three  of  which  are,  however,  so 
far  as  our  present  knowledge  goes  peculiar  to  North 
America.  These  facts  perhaps  justify  the  retention  of 
the  Nearctic  region,  and  they  are  perhaps  also  significant 
in  that  the  peculiar  forms  are  western  in  range — a  possible 
indication  of  their  approaching  extirpation  by  European 
species  introduced  by  commerce. 


SOME  RECENT  MEMOIRS  UPON  OLIGOCHJETA.     193 

The  original  indigenous  forms,  South  American  in 
character,  may  be  regarded  as  having  been  gradually 
driven  to  the  west  by  the  encroachment  of  artificially  in- 
troduced species.  In  other  respects  the  geographical  regions 
indicated  by  the  distribution  of  earthworms  agree  fairly  well 
with  the  generally  received  scheme  of  Mr.  Sclater.  The 
Ethiopian  region  is  peculiarly  distinct  ;  the  Neotropical  is 
also  nearly  if  not  quite  as  plainly  marked  ;  but  the  Oriental 
fades  into  the  Australian,  and  it  is  indeed  not  easy  to 
separate  them  at  all. 

The  only  other  matter  affecting  the  distribution  of  earth- 
worms with  which  I  shall  deal  here  is  the  question  of 
oceanic  islands.  Our  information  upon  the  subject  is  not 
however  by  any  means  extensive  ;  the  largest  collection 
made  is  due  to  the  energy  of  Mr.  Perkins,  and  has  been 
described  by  me  in  a  paper  communicated  to  the  Zoological 
Society.  These  worms  were  gathered  in  the  Sandwich  Is- 
lands, and  belong  to  a  number  of  species  of  which  only  two 
(and  a  doubtful  third)  have  not  been  found  elsewhere ; 
these  two  belong  to  the  genus  Perichccta,  a  genus  prevalent 
in  tropical  regions,  especially  of  the  old  world.  That  the 
bulk  of  the  species  known  from  these  and  other  oceanic 
islands  are  forms  which  have  been  in  all  probability  intro- 
duced by  accidental  transference  by  man  is  rather  what  might 
be  expected  from  the  limited  powers  of  independent  travel 
possessed  by  these  animals.  There  is  at  present  no  certain 
evidence  that  there  are  any  truly  indigenous  earthworms  in 
oceanic  islands,  with  the  exception  of  Kerguelen — a  fact 
which  as  I  have  already  hinted  may  be  due  to  other  causes. 

To  Linnaeus  only  a  single  species  of  earthworm  was 
known,  his  Liimbricus  terrestris,  now  believed  to  have  beeii 
a  compound  of  more  than  one  species.  Grube  in  his 
Familie  der  Anneliden,  published  in  1851,  reckoned  up 
only  forty-two  earthworms,  and  of  these  one  or  two  are 
now  known  not  to  be  earthworms  at  all,  and  of  the  re- 
mainder many  are  unrecognisable  or  synonyms.  Since  that 
period  the  increase  of  new  forms  has  gone  on — of  late 
with  extreme  rapidity ;  at  the  present  moment  we  are 
acquainted  with  rather  over   500   distinct  and    well   char- 


i94  SCIENCE  PROGRESS. 

acterised  species.  And  this  estimate  does  not  take  into 
consideration  subspecies  or  well  marked  varieties,  and  pays 
no  attention  to  "  species  incertae  ".  Of  aquatic  Oligochceta 
150  is  about  the  number  of  known  species  ;  but  this 
group  is  decidedly  less  known  than  the  former.  As  with 
other  groups  of  animals  this  great  increase  in  the  number 
of  known  species  has  added  to  our  knowledge  of  anatomical 
fact,  but  rendered  harder  the  formation  of  classificatory 
schemes.  No  indistinctness,  however,  has  arisen  to  blur 
the  perfectly  sharp  outlines  of  the  group  Oligochaeta,  no 
''intermediate"  forms  have  been  discovered  whose  relega- 
tion to  the  group  is  a  matter  of  uncertainty  or  convenience. 
At  the  same  time  a  few  approximations  in  structure  to  the 
leeches  on  the  one  hand,  and  to  the  Polychseta  on  the 
other  have  been  discovered ;  but  these  are  in  no  case  of 
first-rate  importance.  Perhaps  the  most  remarkable  is  the 
description  of  the  gills  of  the  African  genus  Alma.  This 
worm  was  originally  described  under  that  name  by  Grube 
in  1855.  Thirty-four  years  later  Levinsen,  apparently  in 
ignorance  of  Grube's  paper,  named  a  fragment  of  what  was 
obviously  the  same  worm  Digitibranckus,  and  described  in 
the  same  paper  Siphonogaster,  an  Annelid  characterised  by 
a  pair  of  long  processes  an  inch  or  so  in  length,  and  of  a 
spatula-like  form  arising  from  the  eighteenth  segment. 
These  have  been  subsequently  shown  to  be  processes  con- 
taining the  outer  section  of  the  sperm  duct  which  opens 
near  to  the  extremity.  Michaelsen  showed  that  all  these 
three  worms  are  identical,  and  has  thus  been  able  to  put 
beyond  question  the  existence  of  a  true  earthworm  l  with 
branched  retractile  gills  on  the  posterior  segments  of  the 
body.  It  was  not  by  any  means  clear  from  the  earlier 
descriptions  that  the  gilled  worm  was  not  a  Polychaet. 
Among  the  lower  aquatic  Oligochsetes  there  are  at  least 
three  gilled  forms,  apart  from  Dero  which  has  a  circlet 
of  ciliated  processes,  with  vascular  twigs  lying  round  the 
anus.  These  forms  are  Chcstobranckus  of  Bourne,  and 
Branchiura  and  Hesperodrilus  branchiatus  of  myself.      In 

1  Structurally  ;  in  habit  it  is  aquatic. 


SOME  RECENT  MEMOIRS  UPON  OLIGOCHJETA.     195 

the  two  latter  (which  are  allied  to  Tubifex)  are  contractile 
branchiae,  not  branched  however,  on  some  of  the  posterior 
segments  of  the  body.  More  numerous  are  indications  of 
affinity  with  the  leeches.  I  may,  in  the  first  place,  refer 
to  that  group  of  parasitic  Oligochaeta,  once  placed  among 
the  leeches  but  now  usually  allowed  to  be  true  Oligochaeta, 
for  which  Vejdovsky  has  proposed  the  name  of  Disco- 
drilidae  on  account  of  their  posterior  sucker.  An  American 
genus  Bdellodrilus  has  lately  been  studied  with  care  by 
Moore  whose  results  entirely  confirm  the  placing  of  the 
worms  amono-  the  Oligochaeta  and  their  removal  from  the 
leeches.  Their  chief  points  of  likeness  to  the  Hirudinea  are 
(1)  absence  of  setae  ;  (2)  existence  of  jaws  ;  (3)  presence  of  a 
sucker  ;  (4)  median  unpaired  character  of  reproductive  pores. 
The  first  and  last  of  these  characters  are,  however, 
found  in  a  few  undoubted  Oligochaeta,  for  instance,  Anachczta, 
as  its  name  denotes,  has  no  setae,  and  besides  Mr.  Moore 
describes  large  gland  cells  in  Bdellodrilus  which  may  re- 
present setigerous  cells  of  Oligochaeta.  As  to  the  median 
generative  pores  they  are  very  frequent  among  Oligochaeta. 
The  reproductive  organs  themselves  are  decidedly  upon  the 
Oligochaetous  pattern.  The  gonads  are  entirely  free  from 
their  ducts,  and  there  is  a  single  spermatheca,  a  structure 
entirely  wanting  among  the  true  leeches.  The  male  ducts 
are  two  pairs,  opening  freely  by  ciliated  mouths  into  the 
coelom  and  uniting  into  a  common  terminal  atrium.  Their 
arrangement  recalls  that  of  the  Lumbriculidae.  The  ovaries 
are  proliferations  of  the  coelomic  walls  and  their  contents 
escape  to  the  exterior  by  a  slit  in  the  body  walls  lined  by 
epithelium,  a  kind  of  rudimentary  oviduct  paralleled  in  the 
Enchytraeidae,  and  in  the  Eudrilid  Nentertodrilus.  There 
is  nothing  leech-like  about  the  reproductive  organs,  except- 
ing the  terminal  penis — a  structure,  however,  which  is 
also  found  in  many  Eudrilids  and  in  some  other  Oligo- 
chaeta. The  conclusions  of  the  author  that  the  Disco- 
drilidae  are  Oligochaeta  slightly  modified  for  a  parasitic 
life  is  quite  borne  out  by  their  structure.  We  may  admit 
at  the  same  time  that  this  modification  is  in  the  direction 
of  the  leeches. 

14 


196  SCIENCE  PROGRESS. 

In  addition  to  questions  of  relationship  to  other  neigh- 
bouring groups,  recent  investigation  has  brought  to  light 
facts  of  interest  in  the  anatomy  of  the  Oligochaeta  which 
bear  upon  the  mutual  affinities  of  the  families  and  genera 
into  which  the  order  is  divided.  In  this  direction  the  main 
discoveries  of  importance  relate  to  the  excretory  system.  In 
all  the  simple  aquatic  genera  each  segment  of  the  body 
contains  a  single  pair  of  nephridia  ;  as  a  rule  these  organs 
are  wanting  in  the  anterior  segments,  and  Professor  Bourne 
was  unable  to  find  any  nephridia  at  all  in  Uncinais  littoralis. 
The  absence  of  nephridia  in  the  anterior  segments  of  the 
body,  however,  also  characterises  certain  earthworms.  It 
was  originally  described  by  Perrier  in  Pontodrilus,  and  all 
the  species  of  this  genus  (6)  are  in  the  same  condition. 
More  recently  Benham  and  Risen  have  shown  that  the 
same  state  of  affairs  characterises  the  aquatic  Geoscolecid 
Sparganophilus.  A  distinction  therefore  between  the 
Limicolae  and  Terricolse  of  Claparede  quite  breaks  down. 
That  these  genera  have  no  gizzard  or  calciferous  glands 
(or  at  most  the  rudiments  of  a  gizzard)  is  evidence  of  general 
degradation,  which  may  have  something  to  do  with  their 
aquatic  or  semiaquatic  existence.  It  suggests  too  that 
the  simplification  in  structure  of  the  Limicolae  of  Claparede 
may  be  rather  due  to  degeneration  than  to  the  retention  of 
primitive  characters. 

Among  the  earthworms,  however,  the  single  pair  of 
nephridia  to  each  segment  is  far  from  being  the  rule.  In 
a  large  number  of  genera  the  nephridia  are  multiple.  Two 
pairs  in  each  segment  exist  in  BracJiydriliis ;  three  pairs  in 
Trinephrus;  and  Eisen  has  lately  shown  that  in  certain 
North  American  Benhamias  there  may  be  three  or  four 
distinct  and  separate  pairs  each  with  its  own  internal  funnel 
and  external  pore.  The  complexity  of  the  excretory 
system  culminates  in  Perichceta  where  a  single  segment  may 
be  furnished  with  probably  at  least  one  hundred  external 
nephridiopores.  It  is,  however,  a  question  whether  in 
this  latter  case  there  is  really  an  intercommunication  be- 
tween the  several  nephridia  of  each  segment,  and  between 
those  of  adjacent  segments  as  has  been  alleged  by  Spencer 


SOME  RECENT  MEMOIRS  UPON  0L1G0CHJETA.     197 

and  myself.  The  matter  requires  renewed  investigation. 
In  any  case  Bourne,  Vejdovsky  and  I  have  shown  that  the 
"  plectonephric "  condition,  as  Benham  has  termed  these 
diffuse  nephridial  tubes,  is  preceded  by  a  series  of  paired 
nephridia  one  pair  to  each  segment.  This  has  been  proved 
in  Pericktzta,  Qciochcetus  and  Megascolides.  The  nephridium 
elongates  and  becomes  thrown  into  loops,  each  loop  finally 
appears  in  Megascolides  to  break  away  and  to  form  a 
distinct  and  separate  nephridium.  It  is  clear,  therefore, 
that  whether  or  not  the  connection  is  retained  in  Octochcetris 
and  Perichceta  there  is  originally  a  connection,  so  that  that 
matter  is  of  less  importance  than  the  alleged  intercom- 
munication from  segment  to  segment.  This  multiple 
arrangement  of  the  nephridia  is  only  found  in  the  families 
Acanthodrilidae,  Perichsetidae  and  Cryptodrilidae,  and  is  the 
principal  argument  for  uniting  them  into  one  superfamily, 
Megascolicides,  as  I  have  done  in  my  Monograph.  Brachy- 
drihts,  however,  is  a  member  of  the  family  Geoscolicidse, 
but  it  has  only  two  pairs  of  nephridia  to  each  segment  ; 
there  is  nothing  like  the  complicated  system  of  Perichceta. 
This  family  Geoscolicidse  has  been  through  the  recent  re- 
searches of  Rosa  and  Michaelsen  brought  still  nearer  to  the 
Lumbricidse.  It  was  always  difficult  to  separate  them, 
mainly  on  account  of  the  aquatic  Criodrilus,  now  it  is 
practically  impossible  unless  we  accept  Michaelsen's  inter- 
mediate family  Criodrilidse.  The  ornament  setae  which 
used  to  be  a  distinctive  mark  of  the  Geoscolicidse  have 
been  found  by  Michaelsen  in  Allolobophora  moebii  and 
in  A.  lonnbergi ;  many  Geoscolicidae,  e.g.,  Microckceta  are 
distinguished  by  the  fact  that  instead  of  a  single  pair 
of  spermathecae  in  each  of  those  segments  which  con- 
tain them  there  are  a  considerable  number  of  minute 
pouches ;  this  distinction,  however,  falls  to  the  ground 
since  more  than  one  Allolobophora  is  now  known  to 
possess  the  same  character — which  has  moreover  been  met 
with  in  Perichceta.  It  is  in  these  two  families  that  most 
instances  are  met  with  of  total  absence  of  spermathecae  ; 
Kynotus,  a  Madagascar  genus,  is  anteclitellian  like  the 
Lumbricidae,  and  in  short  it  seems  impossible  to  lay  down  any 


ig8  SCIENCE  PROGRESS. 

set  of  characters  which  should  absolutely  separate  the  two 
families.     Several  members  of  the  two  families  are  aquatic  ; 
thus  among  the  Geoscolicicke  Bilimba  (with  which  Michaelsen 
now  suggests  to  unite  Horst's  A  nnadri/us  and  Glyphidrilus), 
Criodrilus,    whose   range   the   same   author  has   lately  ex- 
tended to  South   America,  Alma  and   Sparganophilus.     Of 
Lumbricidae    Allurus    is     the    only  form    which     is    often 
aquatic.      Michaelsen   has   dwelt  upon  the  fact  that  all  of 
these,    with    the    exception    of    Sparganophilus,    have    the 
body  generally  or  at  least  the    posterior   region  markedly 
quadrangular   in   outlines  with  the   setae   implanted  at  the 
four  corners.     This   is  an  apparent  consequence  or  at  least 
concomitant   of   aquatic    life    which    is    more    curious   than 
explicable.      So  much   then   for  recent  modifications  of  the 
systematic  arrangement  of  the  group.      I   shall  deal  finally 
with  various  anatomical  and  histological  discoveries  which 
have  a  general  interest   unconnected  with  systematic  rela- 
tions.     The   most   important  work   under   this  heading  is 
undoubtedly  the  recent  investigations  into  the  structure  of 
the     remarkable     family   Eudrilidae,  a    well-defined     family 
whose  boundaries  have   not  become  in  the  least   indistinct 
by  the  discovery  of  new  forms.      The  family  is  remarkable 
on  account    of   its    distribution   as    well   as    on  account  of 
certain  anatomical  peculiarities.       It   is   limited  to   tropical 
Africa — to  the  Ethiopian   region  of  Sclater,  with  the  sole 
exception  of  the  type  genus   Eudrilus,  whose  ubiquitous- 
ness,  however  (America,  West   Indies,  India  and  the  East 
generally,   New  Zealand,   etc.),   makes    one   suspect  direct 
transference  by  man.      This  family   is  chiefly  interesting  on 
the  anatomical  side  by  reason  of  the  illustration  which  it 
gives  of  two  phenomena,    viz.,  substitution   of  organs  and 
change    in    function    of   organs. 

In  all  Oligochaeta  the  ovaries  are  paired  (rarely 
unpaired)  structures  which  arise  from  the  peritoneal 
epithelium  of  the  earthworms  invariably  the  thirteenth 
segment.  They  are  totally  unconnected  with  the  oviducts 
whose  open  mouths  are  placed  exactly  opposite  to  them. 
In  the  Eudrilidae  these  gonads  are  enclosed  in  sacs 
which  communicate  with  a  system  of  sacs  the  complexity  of 


SOME  RECENT  MEMOIRS  UPON  OLIGOCHMTA.     199 

which  varies  in  different  genera,  and  of  which  it  would  be 
impossible  to  give  any  detailed  account  without  the  assis- 
tance of  figures.  There  is  a  separate  receptaculum  ovorum 
like  that  of  the  common  earthworm,  with  which  is  connected 
the  oviduct.  This  system  of  sacs,  through  which  the  ova 
can  travel  in  so  far  as  there  are  no  physical  hindrances,  also 
contain  sperm,  and  play  the  part  of  spermatheca?  or  a  sperma- 
theca.  They  commonly  open  by  a  single  ventral  pore  ; 
sometimes  the  structures  are  paired  as  in  the  genus  Eudrilus 
itself.  Now  these  pouches  generally  contain  sperm,  and 
there  is  therefore  the  possibility  of  the  ova  being  impreg- 
nated within  them  ;  Michaelsen  has  even  suggested  that 
some  species  are  viviparous.  In  a  few  genera,  for  example 
in  Heliodrilus,  these  pouches  do  not  communicate  with  the 
exterior  except  through  the  oviducts.  They  appear  to  do 
so  by  a  large  ventral  pore,  but  when  careful  sections  are 
made  it  is  found  that  this  pore  is  the  mouth  of  a  closed  sac, 
exactly  like  a  spermatheca,  which  is  enclosed  within  the 
large  pouch.  Thus  the  ccelomic  nature  of  this  system  of 
sacs  is  established  on  anatomical  grounds,  and  develop- 
mentally  they  have  been  shown,  at  least  in  one  genus,  to 
be  derivatives  of  the  intersegmental  septa  just  as  are  the 
sperm  sacs  of  other  earthworms  ;  their  cavities  are  therefore 
separated  portions  of  the  general  ccelom.  But,  as  already 
mentioned,  in  most  cases  they  do  open  on  to  the  exterior 
directly  by  a  conspicuous  orifice,  and  contain  sperm  which 
probably  finds  its  way  into  them  by  this  orifice.  The  fact 
that  in  some  cases  these  sacs  contain  structures  which  are 
precisely  like  the  spermathecae  of  other  earthworms,  and 
that  in  other  cases  where  they  open  directly  on  to  the 
exterior  the  character  of  the  lining  epithelium  changes  near 
to  the  orifice,  becoming  distinctly  columnar,  suggests  that 
we  have  to  do  here  with  the  substitution  of  sacs  derived 
Irom  the  septa  for  the  true  spermathecae  which  are  gradually 
disappearing,  only  the  extremity  being  left  in  the  majority 
ot  cases.  The  second  point  with  which  I  wish  to  deal 
concerns  the  calciferous  glands.  Most,  but  by  no  means 
all,  earthworms  possess  one  or  more  pairs  of  these  organs, 
which  are  attached  to  and  open  into  the  cesophagus.     What- 


200  SCIENCE  PROGRESS. 

ever  may  be  their  functions  they  contain  crystals  of  car- 
bonate of  lime,  and  have  a  rich  vascular  supply,  the  lining 
epithelium  being  much  folded  and  therefore  extensive.  In 
some  Eudrilidae  these  structures  are  absent  or  rather  are  so 
altered  that  they  are  nearly  unrecognisable  as  calciferous 
glands.  At  the  same  time  they  have  become  more  numerous. 
The  structure  is  altered  in  that  instead  of  an  extensive  lumen 
produced  by  the  folding  of  an  excretory  epithelium  there  is 
a  very  short  sac  connected  with  the  oesophagus,  which 
is,  however,  enveloped  by  an  extensive  coating  of  cells 
which  I  regard  as  ccelomic  cells,  and  among  which  meander 
abundant  blood-vessels.  These  ccelomic  cells,  where  they 
abut  upon  blood-vessels,  very  often  lose  their  oval  or 
rounded  form  and  become  columnar  and  at  the  same  time 
more  darkly  staining.  They  surround  the  blood-vessel  as  if 
it  were  the  lumen  of  a  secreting  gland,  the  cells  themselves 
having  acquired  the  appearance  of  a  secreting  epithelium. 
These  phenomena  suggest  that  we  have  to  do  here  with  a 
change  of  function  on  the  part  of  the  calciferous  glands  ;  that 
their  function  of  producing  carbonate  of  lime,  that  their 
connection  with  alimentation  has  disappeared  or  is  dis- 
appearing, and  that  a  new  function  more  intimately  connected 
with  the  vascular  system  has  supervened.  There  is  a 
certain  analogy  here  with  the  vertebrate  liver  which  has 
certainly  more  functions  than  that  of  pouring  bile  into  the 
intestine,  though  originally  it  may  have  been  merely  an 
annex  of  the  alimentary  canal. 

In  histology  there  is  only  one  matter  to  which  I  shall 
direct  the  attention  of  the  reader.  It  concerns  the  minute 
structure  of  muscular  fibres  in  the  Oligochoeta.  The  careful 
researches  of  Cerfontaine  have  established  the  fact  that  the 
Oligochseta,  like  the  leeches,  have  muscular  fibres  which 
consist  of  an  outer  sheath  often  radiately  striated,  the 
muscular  substance,  and  a  soft  central  core.  Hesse,  how- 
ever, while  admitting  this,  goes  a  step  further  and 
endeavours  to  prove  a  resemblance  to  the  muscular  fibres 
of  the  Nematoidea.  He  figures  in  the  Enchytraeidae  and 
in  the  Lumbricidse  a  gap  in  the  sheath  of  the  fibre  through 
which  the  soft  less-modified  protoplasm  of  the  interior  com- 


SOME  RECENT  MEMOIRS  UPON  OLIGOCH^ETA.     201 

municates  with  a  pear-shaped  nucleated  body  outside.  If 
these  observations  prove  ultimately  to  be  correct  it  is  clear 
that  there  is  a  close  resemblance  in  this  particular  between 
the  Oligochseta  and  the  Nematoidea. 


BIBLIOGRAPHY. 

Beddard.      A    Monograph   of  the    Order   Oligochseta,    Oxford  : 

Clarendon  Press. 
ElSEN.     Pacific  Coast  Oligochaeta.     Mem.  Calif.  Acad.  Set.,  vol.  ii., 

1895-96. 
Hesse.       Beitrage   zur    Kenntniss   des    Baues  der  Enchytraeiden. 

Zcitschr.  fur  iviss  Zoo/.,  1893. 
HESSE.      Zur  vergleichenden  Anatomie  der  Oligochaeten.      Ibid., 

1894. 
MlCHAELSEN.      Zur  Kenntniss  der  Oligochaeten.      Abh.  Nat.  Ver., 

Hamburg,  1895. 
H.  F.  MOORE.     On  the   Structure  of  Bimastos  palustris.    Journ. 

Morph.,  1895. 
J.  P.  MOORE.     The  Anatomy  of  Bdellodrilus  illuminatus.     Ibid. 
ROSA.      Allolobophora  dugesii.      Boll.  Mus.  Zooi,  Torino,  1895. 
BOURNE.     In  Quart.  Journ.  Micr.  Sci.,  1894. 
SMITH.     Notes  on  Species  of  North  American  Oligochaeta.     Bull. 

Illinois  State  Lab. 

F.  E.   Beddard. 


NOTES  ON  ATOMIC  WEIGHTS. 

IN  a  former  article 1  a  sketch  of  the  state  of  our  know- 
ledge as  to  the  relative  atomic  weights  of  hydrogen  and 
oxygen  was  given.  It  was  there  shown  that  although  the 
great  mass  of  the  evidence  was  in  favour  of  the  atomic 
weight  of  oxygen  being  about  15*88  times  that  of  hydrogen 
yet  there  was  a  certain  amount  of  experimental  work  by 
well-known  and  tried  observers  which  seemed  irreconcilable 
with  this  result,  the  chief  paper  (1)  being  that  of  Professor 
Julius  Thomsen  of  Copenhagen,  and  based  on  the  propor- 
tion by  weight  in  which  ammonia  and  hydrochloric  acid 
combine  to  form  neutral  ammonium  chloride.  In  a  short 
paper  by  the  late  Lothar  Meyer  (2)  it  was  proved  con- 
clusively how  little  value  could  be  attached  to  a  determina- 
tion of  this  nature  however  accurate  and  careful  the  mani- 
pulative work  might  be. 

Any  hopes  which  might  have  survived  in  the  minds  of 
the  most  ardent  follower  of  Prout,  that  the  atomic  weight 
of  oxygen  is  exactly  sixteen  times  that  of  hydrogen,  must 
now  be  dispelled  by  the  recent  publications  of  E.  W. 
Morley  (3)  and  of  Thomsen  (4)  himself.  The  work  of 
Morley  is  so  conclusive,  and  has  been  carried  out  with 
such  untiring  patience  and  skill,  that  to  any  one  who  reads 
the  clear  account  which  he  gives  of  his  methods  and  of  the 
various  checks  employed,  it  must  be  quite  evident  that  that 
type  of  worker  of  whom  we  regard  Stas  as  the  chief  is  not 
yet  extinct,  in  spite  of  the  prevailing  view  that  one  must 
publish  as  many  papers  as  possible  in  the  least  possible 
time  before  one  can  be  said  to  engage  in  "  original  re- 
search ".  Morley's  scheme  for  the  complete  determination 
of  the  relative  atomic  weights  of  oxygen  and  hydrogen  is 
a  most  ambitious  one,  and,  although  his  results  are  quite 
conclusive  now,  it  is  much  to  be  regretted  that  bad  health 
and  other  circumstances  over  which  he  had  no  control 
(such  as  a  workman  pushing  a  brick  through  a  wall  on  to  a 

1  August,  1894. 


NOTES  ON  ATOMIC  WEIGHTS.  203 

delicate  piece  of  glass  apparatus)  have  up  to  the  present 
time  prevented  him  from  carrying  out  his  original  pro- 
gramme in  its  entirety. 

The  paper  consists  of  four  distinct  parts — 

I.  The  determination  of  the  weight  of  a  litre  of  oxygen. 

II.  The    determination    of   the    weight    of  a    litre    of 

hydrogen. 

III.  The   ratio   by  volume  in  which  these  two  gases 

combine  to  form  water. 

IV.  The  synthesis  of   water  from   known  weights  of 

hydrogen  and  oxygen,  the  weight  of  the  water 
formed  being  also  accurately  determined. 

It  would  be  impossible  to  give  any  idea  of  the  precau- 
tions taken  to  obtain  results  free  from  all  objections  in  a 
sketch  so  short  as  this  must  be,  for  such  details  the 
original  memoir  must  be  consulted ;  only  a  summary  of 
the  results  obtained  can  here  be  given. 

Three  methods  were  adopted  to  determine  the  weight 
of  a  litre  of  oxygen.  In  the  first  method  the  barometer 
and  thermometer  were  used,  and  the  gases  weighed  in 
balloons  holding  in  three  of  the  experiments  about  9  litres, 
and  in  the  other  six  about  21^  litres. 

In  the  second  method  a  globe  of  pure  and  dry  hydrogen 
was  used  as  the  standard  for  temperature  and  pressure,  the 
globe  containing  the  oxygen  having  its  pressure  deter- 
mined at  the  same  temperature  as  that  of  the  hydrogen 
by  means  of  a  very  sensitive  differential  manometer. 

In  the  third  method  the  globes  were  filled  with  oxygen 
when  they  were  immersed  in  melting  ice  and  the  pressure 
accurately  determined  at  the  moment  of  closing.  This 
method  had  the  disadvantage  of  wetting  the  surface  of  the 
globes,  and  probably  thereby  changing  their  weight  (although 
this  was  duly  investigated). 

The  values  obtained  by  these  three  methods  for  the 
weight  of  1  litre  of  oxygen  under  normal  conditions  of 
temperature  and  pressure  at  sea  level  in  lat.  450  were 

By  use  of  thermometer  and  manometer-     0  =  1-42879  +  "000034. 
By  compensation       -  0=1-42887  +  -000048. 

By  use  of  ice  and  barometer        -         -     0  =  1*42917  +  -000048. 


204  SCIENCE  PROGRESS. 

From  various  considerations  taking  into  account  errors 
incidental  to  certain  methods  and  liability  to  constant  errors 
Morley  gives  the  most  probable  value  as  i  "42900 ±0*000034. 

In  the  same  way  experiments  were  made  with  hydrogen 
and  in  live  series  but  practically  by  three  methods. 

First  method  was  practically  the  same  as  the  first  series 
of  oxygen  experiments. 

Second  method  was  like  the  third  oxygen  series. 

Third  method  utilised  the  power  of  absorbing  hydrogen 
possessed  by  palladium.  The  hydrogen  was  weighed  in 
the  palladium  and  expelled  into  globes,  and  its  volume  and 
pressure  determined  at  the  temperature  of  melting  ice. 
Series  III.,  IV.  and  V.  were  made  by  this  method,  but 
the  apparatus  employed  varied  somewhat  in  the  various 
series. 

The  values  which  result  from  these  experiments  are 

Series      I.   Dh  =  -089938  gram. 

Series    II.  Dh  =  '089970  gram. 

Series  III.   Dh  =  -089886  +  -0000049  gram. 

Series  IV.  Dh  =  -089880  +  -0000088  gram. 

Series   V.  Dh  =  -089866  +  -0000034  gram. 

The  higher  results  of  Series  I.  and  II.  are  possibly  due  to 
some  constant  error,  probably  traces  of  mercury  vapour. 
The  most  probable  value  is 

Dh  =  -089873  +  0*0000027  gram. 

Part  III.  of  the  paper  begins  with  a  sketch  of  the  methods 
it  was  proposed  to  employ  to  determine  the  volumetric 
composition  of  water.  Of  the  three  methods  proposed  Morley 
unfortunately  has  only  been  able  to  carry  out  the  one  which 
is  the  least  satisfactory,  viz.,  the  determination  of  the 
density  of  electrolytic  gas  and  of  the  excess  of  hydrogen 
over  and  above  what  the  oxygen  can  unite  with.  Leduc 
made  a  similar  density  determination,  but  apparently 
assumed  that  the  hydrogen  and  oxygen  were  in  the  exact 
proportions  in  which  they  would  recombine  to  form  water. 
Morley  found  that  he  always  had  an  excess  of  hydrogen 
when  he  kept  his  voltameter  in  ice  and  water,  but  that 
when  the  temperature  was  allowed  to  rise  to  about  20°  C. 
then  oxygen  was  in   slight   excess,    so  that  no  doubt   at  a 


NOTES  ON  ATOMIC  WEIGHTS.  205 

certain  temperature  the  gases  do  come  off  in  atomic  propor- 
tions. In  each  experiment  the  weight  of  the  gases  given 
off  was  about  23  grams. 

The  weight  of  a  litre  of  the  gas  thus  given  off  from 
solution  of  soda  made  from  clean  sodium  was — 

°'53551Q  ±  o-ooooio, 
and  corresponds  to  a  mixture  of  one  volume  of  oxygen  with 
2*00357  volumes  of  hydrogen,  but  the  excess  of  hydrogen 
was  found  to  be  -ooo88  giving  therefore  the  ratio  in  which 
the  gases  combine  as  1  :  2*00269. 

Part  IV.  gives  an  account  of  experiments  in  which 
hydrogen  was  weighed  in  palladium  foil,  oxygen  was 
weighed  in  a  globe,  these  were  then  made  to  combine,  and 
the  water  produced  was  weighed  also. 

From  these  experiments  we  get  the  following  values  for 
the  atomic  weight  of  oxygen  : — 

(1)  From  the  ratio  of  hydrogen  and  oxygen,         -         -     15-8792 

(2)  From  the  ratio  of  hydrogen  and  water,  -         -         -     15-8785 

or  as  a  mean,    ------     15879 

From  Parts  I.,  II.,  III.  of  the  memoir  we  get 

1*42000        2  0 

—17~ x  =  15-879 

•089873       2-00269 

How  excellent  Morley's  work  is  can  perhaps  best  be 
seen  by  comparing  his  results  with  the  means  of  those  of 
previous  experimenters, 

Rayleigh's 

summary.  Morley. 

Density  of  oxygen  at  Paris,        -         -     1-42961  1-42945 

Density  of  hydrogen  at  Paris,    -         -       -08991  -089901 

Ratio  of  densities  mean  of  all  previous  determinations,  -  -  15-9005 
Ratio  of  densities,  Morley's, 15-9002 

Ratio  of  combining  volumes,  Morley,  -     2*00269 
„  ,,  Scott,      -     2*00285 

,,  ,,  Leduc,    -     2*0037  (corrected  =  2  0024) 

Although  the  results  obtained  by  Thomsen  agree 
wonderfully  well  with  those  of  Morley  it  is  not  because  his 
apparatus  and  his  methods  of  working  are  so  carefully 
elaborated.  On  the  contrary  what  strikes  one  most  forcibly 
is   the   extreme  simplicity  of  the   apparatus  and  mode   of 


206  SCIENCE  PROGRESS. 

working  it  as  well  as  the  neglect  of  certain  precautions 
which  could  well  have  been  taken,  and  ought  to  have  been 
taken  in  an  attempt  to  settle  such  an  important  constant  as 
the  present ;  such  precautions  as  to  weighing  with  counter- 
poises of  equal  volume,  for  example,  seem  to  have  been 
neglected. 

The  method  was  to  determine,  firstly,  the  weight  of 
hydrogen  given  off  from  unit  weight  of  aluminium  when 
dissolved  in  strong  potash  solution  ;  secondly,  by  supplying 
oxygen  to  a  small  combustion  chamber  so  as  to  burn  the 
hydrogen  evolved  from  a  known  weight  of  aluminium,  and 
collect  all  the  water  formed  in  the  apparatus,  one  gets  thus 
the  gain  of  the  equivalent  amount  of  oxygen  to  the  hydro- 
gen and  to  the  aluminium.  The  only  corrections  not  of 
the  simplest  order  were  due  to  the  oxygen  and  hydrogen 
remaining  in  the  apparatus  or  which  had  to  be  evolved  after 
the  combustion  had  ceased.  It  was  not  found  possible  to 
burn  all  the  hydrogen  evolved  completely  as  the  current 
became  so  very  slow  when  a  very  little  aluminium  remained 
undissolved.  The  aluminium  did  not  require  to  be  perfectly 
pure  as  long  as  it  gave  off  no  other  gas  than  hydrogen.  It 
was  found  that  162 "3705  grams  of  aluminium  gave  off 
1 8*1778  grams  of  hydrogen  giving  the  ratio 

Hydrogen 

p —  =  0*111902  +  "000015 

Aluminium 

as  the  mean  of  twenty-one  experiments. 

The  weight  of  oxygen  required  to  combine  with  86*9358 
grains  of  aluminium  (or  rather  with  the  hydrogen  evolved 
by  its  solution  in  potash)  was  found  to  be  yyiSyG  grams 
from  which  we  get  the  ratio 

°*W^  =  -88787  ±00001 S 
Aluminium 

from  which  two  results  we  get 

O       -88787 

5-  =  — —    =  7 '9345 

Ho       '11190 

or    —  =  i?-86qo  +  "oo22 
H         D  ~ 

We  seem  to  have  every  reason  now  to  regard  it  as  com- 
pletely proved  that  the  atomic  weight  of  oxygen  is  15*87  to 


NOTES  ON  ATOMIC  WEIGHTS.  207 

r  5*88  times  that  of  hydrogen,  the  higher  value  being  in  all 
probability  the  more  correct. 

Having   now  satisfactory  determinations  of  our  funda- 
mental ratio  we  still  require  other  ratios  to  be  able  to  de- 
termine conveniently  the  atomic  weights  of  many  elements. 
If  an  element  forms   many  compounds   with   oxygen   it   is 
never  safe  to  conclude  without  the  most  rigorous  proof  that 
we  have  a  pure  oxide  absolutely  free  from  the  other  oxides 
of  the    same    element.      Hence  determinations  of  atomic 
weights  made  by  the  reduction  of  oxides  to  the  element  or 
of   one    oxide    to    a    lower   one   or   of   the  oxidation  of  an 
element  to  an  oxide  or  of  one  oxide  to  a  higher  oxide  must 
always  be  accepted  with   caution.     The  use  of  the  haloid 
compounds  (especially  those  of  bromine),  of  many  elements, 
is  of  the  greatest  value,  and  for  this  we   require  an  exact 
knowledge  of  the  ratio  bromine  :    oxygen.      For  this  we 
depend  chiefly  on  the  classical  work  of  Stas.      The  publica- 
tion of  the  complete  works  (5)  of  J.  S.   Stas  under  the  able 
editorship  of  Professor  W.  Spring,  of  Liege,  enables  every 
one  now  to  obtain  in  an  elegant  and  convenient  form  these 
models  and  masterpieces  of  accurate   research  which  were 
formerly  so  difficult  to  procure.      How  great  the  contrast 
between  the  work  of  Stas  and  too  much  of  that  turned  out 
at    the    present    day    a    glance  at  almost  any  page  of   his 
works  will  show.      Every  step  was  proved  most  conclusively, 
however  simple  and  even  axiomatic  it  may  seem  to  us  now, 
before  he    proceeded   to   more  elaborate  propositions   and 
deductions.     For  instance,  in  his  Nouvelles  Recherches  he 
begins  by  proving  that  ammonium  chloride  prepared  from 
absolutely  different  sources  and   purified   in   different  ways 
always  contains   exactly   the  same   proportion   of  chlorine, 
and    that    the    same    weight    of   each    sample    precipitated 
exactly    the   same    amount   of   silver   from  its    solution    in 
nitric  acid.      He  obtained  his  ammonia  from  ordinary  sal 
ammoniac  after  destroying  any  organic  bases    by  a   treat- 
ment  with   aqua   regia,  and    from  commercial    ammonium 
sulphate  by  a  similar  purification,  by  heating  it  to  a  high 
temperature  with  strong  sulphuric  acid,  and  then  oxidation 
with  nitric  acid,  and  from  potassium  nitrite  by  reduction  in  an 


2o8  SCIENCE  PROGRESS. 

alkaline  solution  with  purified  metallic  zinc.  The  ammonium 
chloride  was  sublimed  now  in  a  current  of  ammonia  gas, 
now  in  vacuo,  but  the  results  obtained  showed  that  for  the 
complete  precipitation  of  100,000  parts  of  silver,  49,592  to 
49,602  parts  of  ammonium  chloride  were  required.  In 
other  words,  the  extreme  difference  in  a  large  number  of 
determinations  carried  out  with  very  considerable  modifica- 
tions only  amounted  to  one  part  in  five  thousand. 

Having  thus  proved  that  a  compound  always  contains 
the  same  proportion  of  its  constituent  elements  it  was 
essential  for  his  purpose  as  well  as  for  the  complete 
establishment  of  the  atomic  theory  to  prove  that  the  equiva- 
lent weight  of  an  element  was  not  affected  in  the  slightest 
degree  by  the  various  elements  with  which  it  might 
combine.  To  take  an  example,  silver  combines  with 
iodine  to  form  the  iodide,  and  with  iodine  and  oxygen  to 
form  the  iodate,  and  these  compounds  are  represented  by 
the  formulae  Agl  and  Ag  I03  respectively.  It  was  just 
possible,  one  might  even  say  probable,  that  the  ratio  of  silver 
to  iodine  in  the  one  compound  might  not  be  the  same  as 
that  in  the  other,  but  that  it  would  be  modified  by  the  large 
quantity  of  oxygen  present  in  that  other  substance.  If, 
however,  the  elements  consist  of  small  particles  alike  in  all 
respects,  such  a  variation  would  be  impossible,  and  the 
relative  masses  of  silver  and  iodine  in  the  iodide  and  in  the 
iodate  must  be  absolutely  the  same.  To  prove  this  may 
seem  very  easy,  but  Stas  found  it  by  no  means  so,  lor 
whenever  he  prepared  his  silver  iodate  by  precipitation  from 
the  nitrate,  after  the  reduction  with  sulphurous  acid  there 
was  always  a  small  excess  of  silver  over  and  above  the 
iodine  present.  This  he  finally  traced  to  a  minute  quantity 
of  the  nitrate  being  carried  down  mechanically  by  the 
iodate,  but  so  firmly  held  that  no  amount  of  washing  would 
remove  it.  By  using  other  soluble  salts  of  silver  such  as 
the  sulphate  and  the  dithionate,  however,  he  was  able  to 
prepare  silver  iodate  so  pure  that  on  reduction  to  silver 
iodide  not  the  slightest  trace  of  either  silver  or  iodine  re- 
mained  in  excess.  In  the  case  of  that  prepared  from  the 
nitrate  the  excess  of  silver  only  amounted  to  one  part  in 


NOTES  ON  ATOMIC  WEIGHTS.  209 

3,000,000.  These  simple  experiments  give  us  some  idea 
as  to  how  hard  it  is  to  obtain  even  very  simple  compounds 
in  a  state  of  absolute  purity.  Having  thus  laid  the  founda- 
tions for  his  further  work,  and  shown  that  the  combining 
proportions  of  elements  are  mathematically  exact,  Stas  con- 
sidered no  labour  too  great  if  thereby  he  could  obtain  more 
accurate  values  for  these  proportions.  Any  work  done 
since  his  determinations  has  only  tended  to  uphold  his 
values  and  to  increase  our  admiration  for  his  work. 

The  great  value  of  very  accurate  experimental  work 
has  been  most  strikingly  exemplified  by  Lord  Rayleigh's 
determinations  of  the  density  of  nitrogen  (6).  He 
found  that  the  nitrogen  which  he  could  obtain  from  air 
alone  by  removing  the  oxygen  was  very  little  denser,  but 
was  always  denser  than  that  prepared  from  the  air  with  the 
aid  of  ammonia  by  Harcourt's  method,  and  that  the  nitro- 
gen prepared  from  ammonia  or  from  any  compound  had 
always  the  same  density,  and  that  this  was  still  lighter  than 
that  partly  from  air  and  partly  from  ammonia.  From  this 
he  concluded  that  besides  nitrogen  the  atmosphere  must 
contain  another  constituent  still  denser,  which  like  nitrogen 
resisted  the  action  of  iron  and  copper  as  well  as  their  oxides, 
even  when  very  strongly  heated.  By  combining  the 
nitrogen  with  oxygen  after  the  method  of  Cavendish,  or  by 
causing  the  nitrogen  to  unite  with  metallic  magnesium,  a 
new  gas  to  which  the  name  of  argon  has  been  given  was 
finally  separated  by  Rayleigh  and  Ramsay  after  much 
laborious  work.  The  detection  in  the  atmosphere  of  a 
constituent  hitherto  unsuspected  as  well  as  its  isolation  are 
apparently  only  the  first  fruits  of  a  number  of  more  or  less 
startling  discoveries  Mowing  directly  from  Lord  Rayleigh's 
very  accurate  work.  The  molecular  weights  of  argon 
(7)  and  helium  (8)  are  respectively  40  and  4,  and  if  their 
molecules  are  monatomic  this  would  give  us  the  same 
numbers  for  their  atomic  weights,  but  if  the  molecules  are 
diatomic,  as  is  probable,  these  numbers  would  be  halved  for 
the  atomic  weights.  It  is  far  from  certain  that  either  what 
we  call  argon  or  what  we  call  helium  is  not  a  mixture  of 
several  similar  substances. 


210  SCIENCE  PROGRESS. 

Several  atomic  weights  have  been  redetermined  with 
great  care,  and  of  these  determinations  perhaps  those 
of  T.  W.  Richards  of  barium  and  of  strontium  are  the  most 
accurate  and  most  interesting.  By  an  exhaustive  research 
on  barium  bromide  he  deduces  the  value  Ba  =  137*434 
(O  =  16)  (9).  From  a  similar  study  of  barium  chloride  the 
value  Ba  =  137*440  is  deduced  (10). 

This  value  is  notably  higher  than  that  usually  accepted 
and  is  no  doubt  due  to  the  careful  elimination  of  small 
quantities  of  strontium  and  calcium  which  have  contaminated 
the  preparations  of  earlier  experimenters.  From  a  study  of 
strontium   bromide    Richards   found    Sr  =  87*659    (O  =  16) 

Still  more  recently  the  atomic  weight  of  zinc  has  been 
determined  by  Richards  and  Rogers  again  by  means  of  the 
bromide  and  precipitation  with  silver,  and  as  a  mean  they 
find  the  value  (Zn  =  65*404)  (O  =  16)  (12). 

In  all  the  above  determinations  Richards  estimated  the 
percentage  of  silver  in  his  haloid  silver  salt  and  showed  it 
to  be  identical  with  that  found  by  Stas,  thus  placing  his 
work  on  the  same  footing  and  guaranteeing  in  this  way  its 
very  high  accuracy. 

In  1888  two  other  American  experimenters,  Burton  and 
Morse  (13),  published  the  results  of  their  work  on  the  same 
atomic  weight  which  they  arrived  at  by  means  of  the  con- 
version of  the  metal  into  the  oxide  by  treatment  with  nitric 
acid  and  ignition  of  the  nitrate.  Although  their  work 
agrees  throughout  very  well  the  value  found  is  lower  than 
that  of  Richards,  due  no  doubt  to  the  retention  by  the 
oxide  of  oxides  of  nitrogen  as  Marignac  pointed  out.  In 
defending  their  work  against  this  objection  they  expose 
their  want  of  knowledge  of  the  commonest  reactions  in  such 
a  way  as  to  make  one  distrust  all  their  work.  The  perusal 
of  their  paper  provides  much  food  for  reflection  of  a  serious 
nature  although  it  does  give  a  certain  amount  of  instruction 
as  well  as  amusement.  They  carry  out  their  weighings  to 
*ooooi  of  a  gram  and  pretend  to  detect  differences  of  this 
minute  amount  in  porcelain  crucibles  which  have  been 
heated  up  to  the  melting  point  of  steel.      In  their  account 


NOTES  ON  ATOMIC  WEIGHTS.  211 

of  the  purification  of  metallic  zinc  by  distillation  in  vacuo  it 
is  rather  odd  to  find  it  stated  that  indiarubber  tubing  with 
glycerine  joints  could  not  be  used  because  the  vapours  of zinc 
and  of  glycerine  interact.  What  pressure  of  the  vapour  of 
each  is  likely  to  exist  at  the  highest  temperature  to  which  the 
joints  would  ever  be  subjected  ?  The  presence  of  gold  in 
the  nitric  acid  distilled  from  a  platinum  still,  and  coming 
from  the  gold  solder  used  in  it  sounds  also  rather  peculiar. 
One  knows  that  very  finely  divided  gold  will  dissolve  in 
fuming  nitric  acid  if  kept  cold,  but  one  could  hardly  have 
thought  of  finding  it  as  an  impurity  in  nitric  acid  prepared 
by  distillation.  But  the  gem  of  all  the  statements  comes  at 
the  end  of  the  paper  when  these  two  rising  experimentalists 
proceed  to  criticise  Marignac's  work  (14),  and  finally  to 
teach  him  and  us  how  we  ought  to  test  for  oxides  of  nitro- 
gen by  means  of  starch  and  potassium  iodide.  After 
proving  to  their  own  satisfaction  by  a  process  which  cannot 
reveal  the  presence  of  any  of  these  oxides  that  they  are 
therefore  obviously  absent,  they  conclude  that  Marignac 
was  ignorant  of  the  necessary  precautions  which  must  be 
taken  to  exclude  oxygen,  especially  that  of  keeping  the 
solution  practically  boiling  so  that  the  steam  may  keep  out 
the  air.  It  is  usually  accepted  as  a  well-established  fact 
that  the  delicacy  of  this  reaction  decreases  rapidly  with  rise 
in  temperature,  and  that  the  colour  goes  completely  before 
the  boiling  point  is  reached,  even  in  the  presence  of 
relatively  large  quantities  of  free  iodine. 

Amongst  other  noteworthy  determinations  of  atomic 
weights  made  recently  are  those  of  Winkler,  who  finds 
the  values  Ni  =  58*91  and  Co  =  59*67  by  means  of  the 
reaction  between  the  chlorides  and  silver  (15);  and  still 
more  recently  Ni  =  5871  and  Co  =  59*37  (16)  by  deter- 
mining the  amount  of  iodine  required  to  unite  with  the 
pure  metal.  Winkler  uses  the  value  Ag  =  107*66,  if  we 
use  O  =  16  or  Ag  =  107*93  these  last  values  become 

Ni  =  58-863 
Co  =  59*517 

The  determinations  of  the  atomic  weight  of  boron  by 

15 


212  SCIENCE  PROGRESS. 

Ramsay  and  Acton  (17),  as  well  as  by  Rimbach  (18),  are 
very  interesting  as  examples  of  various  methods  of  attacking 
this  problem,  and  which  give  fair  results,  but  they  can 
hardly  be  said  to  have  given  results  possessing  greater 
accuracy  than  those  of  Abrahall  (19). 

Of  all  the  elements  of  which  the  atomic  weights  are  still 
in  doubt,  and  of  which  the  determinations  are  very  unsatis- 
factory, by  far  the  most  interesting  is  undoubtedly  tellurium. 
According  to  the  periodic  classification  of  the  elements  it 
ought,  as  is  well  known,  to  have  an  atomic  weight  less  than 
that  of  iodine,  but  all  the  most  satisfactory  determinations 
are  irreconcilable  with  this,  and  make  the  atomic  weight 
notably  higher  than  that  of  iodine.  The  experiments  made 
in  recent  years  both  by  Brauner  (20)  and  by  Wills  (21) 
agree  in  this,  no  matter  what  method  is  adopted  as  long  as 
it  is  one  which  gives  concordant  results.  The  latest  deter- 
minations, those  of  Staudenmeier  (22)  which  start  from 
telluric  acid,  give,  according  to  him,  the  values  127*6, 
127*1,  and  127*3  f°r  three  series  of  experiments  in  which 
different  ratios  were  determined.  He  takes  as  his  standard 
O  =  16  and  H  =  1*0032.  Staudenmeier  upholds  that  tel- 
lurium is  an  element  in  opposition  to  Brauner  who  at  one 
time  maintained  that  it  was  a  mixture  of  true  tellurium  with 
a  higher  homologue,  but  now  concludes  that  this  is  very  im- 
probable, and  since  the  discovery  of  argon  suggests  that 
the  assumed  impurity  may  be  a  homologue  of  argon. 
Speculations  of  this  nature  are  strongly  to  be  discouraged 
and  condemned,  especially  when  their  basis  is  nothing 
more  than  the  assumed  abnormality  in  the  periodic  ar- 
rangement of  the  elements  coupled  with  a  very  decided 
want  of  agreement  in  the  results  of  an  experimenter's  own 
work  obtained  by  different  methods.  They  may  afford  an 
easier  way  out  of  a  difficulty  than  by  working  steadily  at 
the  causes  of  such  discrepancies,  but  afford  at  best  but  a 
feeble  and  undignified  cover  for  one's  retreat. 

P.S. — About  the  middle  of  last  month,  and  after  the 
above  article  was  written,  Thomsen  (23)  published  the 
results  of  some  new  determinations  of  the  densities  of 
oxygen    and    hydrogen.       The    oxygen    was    prepared    by 


NOTES  ON  ATOMIC  WEIGHTS.  213 

heating  a  mixture  of  potassium  chlorate  and  ferric  oxide, 
and  the  hydrogen  from  a  solution  of  caustic  potash  by  the 
action  of  metallic  aluminium.      The  values  found  were  : — 

Weight  of  one  litre  of  oxygen  at  0°  C.  and  760  mm.  pressure,  at 
sea-level  in  Latitude  45°  -         -         -     =  1*42906    grams. 
And  of  hydrogen  similarly  =    -089947  gram. 

From  these  he  deduces  the  ratio  of  the  volumes  in  which 
they  must  combine  to  form  water  to  be  1  :  2*00237. 


BIBLIOGRAPHY. 

(1)  Thomsen,  J.     Experimentelle  Untersuchungen  zur   Feststel- 

lung  des  Verhaltnisses  zwischen  den  Atomgewichten  des 
Sauerstoffs  und  Wasserstoffs.  Zeitschrift  fur  physikalisdie 
Chemie,  xiii.,  398,  1894. 

(2)  Meyer,  L.,  und  Seubert,  K.      Ueber  das  Verhaltniss  der 

Atomgewichte  des  Wasserstoffes  und  des  Sauerstoffes. 
BericJite  ler  deutsclien  chemischen  Gesellschaft,  xxvii.,  2770- 
2773,  1894. 

(3)  Morley,  E.  W.     On  the  Densities  of  Oxygen  and  Hydrogen, 

and  on  the  Ratio  of  their  Atomic  Weights.  Smithsonian 
Contributions  to  Knoivlcdge,  No.  980,  1895. 

(4)  THOMSEN,  J.     Experimentelle  Untersuchung  iiber  das  Atom- 

gewichts  verhaltniss  zwischen  Sauerstoff  und  Wasserstoff. 
ZeitscJirift  fur  anorganische  CJiemie,  xi.,  14,  1896. 

(5)  STAS,   J.    S.      Giuvres   completes.      Edited   by    Professor  W. 

Spring,  Bruxelles,  1894. 

(6)  Rayleigh,   Lord.     On  an  Anomaly  Encountered  in  Deter- 

minations of  the  Density  of  Nitrogen  Gas.     Proceedings  of 
the  Royal  Society,  lv.,  340,  1 894. 

(7)  Rayleigh  and  Ramsay.     Argon,  a  New  Constituent  of  the 

Atmosphere.  Philosophical  Tra?isaction±,  clxxxvi.,  A.  223, 
1895. 

(8)  Ramsay,    W.      Helium    a  Constituent   of  Certain    Minerals. 

Journal  of  the  CJiemical  Society,  Ixvii.,  684,  1895. 

Langlet,  N.  A.     Ueber   das  Atomgewicht  des  Heliums. 

Zeitschrift  fur  anorganische  Chemie,  x.,  289,  1895. 

(9)  Richards,    T.  W.      A  Revision    of  the  Atomic  Weight  of 

Barium  ;  the    Analysis    of  Baric   Bromide.     Proceedings   of 
the  American  Academy  of  Arts  and  Sciences,  xxviii.,  1-30, 
1893. 


214  SCIENCE  PROGRESS. 

(10)  RICHARDS,  T.  W.  A  Revision  of  the  Atomic  Weight  of 
Barium;  the  Analysis  of  Baric  Chloride.  Proceedings  of  the 
American  Academy  of  Arts  and  Sciences,  xxix.,  55-91,  1893. 

(n)  RICHARDS,  T.  W.  A  Revision  of  the  Atomic  Weight  of 
Strontium ;  the  Analysis  of  Strontic  Bromide.  Proceedings 
of  the  American  Academy  of  Arts  and  Sciences,  xxx.,  369- 
389,  1894. 

(12)  RICHARDS,  T.  W.  and  ROGERS,  E.   F.     Neubestimmung  des 

Atomgewichtes  von  Zink  ;  analyse  von  Zinkbromid.  Zeit- 
schrift fiir  anorganische  CJiemie,  x.,  1-24. 

(13)  Morse,   H.  N.  and  Burton,  W.  M.     The  Atomic  Weight 

of  Zinc  as  Determined  by  the  Composition  of  the  Oxide. 
American  Chemical  Journal,  x.,  31 1-32 1,  1888. 

(14)  Marignac,C.DE.     Verification  de  quelques  poids  atomiques  : 

Zinc.  Archives  des  sciences  physiques  et  naturelles  [3]  x.,  193, 
1883. 

(15)  Winkler,   C.      Ueber  die  vermeintliche  Zerlegbarkeit    von 

Nickel  und  Kobalt  und  die  Atomgewichte  dieser  Metalle. 
Zeitschrift  fiir  anorganische  Chemie,  iv.,  10  and  462, 
1893. 

(16)  Winkler,  C.     Die  Atomgewichte  von  Nickel  und  Kobalt. 

Zeitschrift  fiir  anorganische  Chemie,  viii.,  291,  1895. 

(17)  RAMSAY,    W.    and    ASTON,    E.      The    Atomic    Weight   of 

Boron.     Journal  of  the   Chemical  Society,  lxiii.,   207,    1893. 

(18)  RlMBACH,    E.      Zum    Atomgewicht  des  Bors.     Berichte  der 

deutschen  chemischen  Gesellschaft,  xxvi.,  164,  1893. 

(19)  ABRAHALL.     The  Atomic  Weight  of  Boron.    Journal  of  the 
Chemical  Society,  Ixi.,  650-666,  1892. 

(20)  BRAUNER,    B.       Experimental    Researches    on    the    Periodic 

Law.     Journal  of  the  Chemical  Society,  lv.,  382-411,  1889. 

(21)  Wills,  W.  L.     On  the  Atomic  Weight  of  Tellurium.    Journal 

of  the  Chemical  Society,  xxxv.,  704-713,  1879. 

(22)  Staudenmeier,     L.       Untersuchungen     iiber     das    Tellur. 

Zeitschrift  fur  anorganische  Chemie,  x.,  189,  1895. 

(23)  Thomsen,  J.     Experimentelle  Untersuchung  iiber  die  Dichte 

des  Wasserstoffes  und  des  Sauerstoffes.  Zeitschrift  fib 
anorganische  Chemie,  xii.,   1-1 5,   1896. 

Alexander  Scott. 


THE   STELAR  THEORY;    A   HISTORY  AND  A 

CRITICISM. 

PART  II. 
THE  METAMORPHOSES  OF  THE  STELE. 

IT  is  clear  that  the  theory  of  polystely  forms  an 
integral  part  of  the  general  stelar  doctrine,  and  we 
can  hardly  refuse  to  accept  its  main  idea.  But  though  each 
stele  in  the  polystelic  stems  of,  for  instance,  Aiiricula  Ursi 
and  many  Polypodiacea^  is  clearly  the  equivalent  of  the 
whole  cylinder  in  the  hypocotyl  of  the  same  plants,  cases 
exist  in  which  we  seem  forced  to  consider  as  steles, 
vascular  strands  which  have  none  of  the  characters  of  the 
cylinder  left  about  them. 

Deriving  our  idea  of  the  typical  stele  from  the  mono- 
stelic  organ,  we  come  to  consider  it  as  essentially  cylindrical 
and  radially  symmetrical.  It  is  true  that  diarch  roots  are 
bilateral  in  structure,  and  the  primary  root  and  hypocotyl  of 
very  many  ferns  being  diarch  the  steles  of  a  great  number 
of  their  stems  are  likewise  diarch  and  hence  bilateral.  And 
this  bilaterality  often  extends  to  the  shape  of  the  stele  which 
becomes  oval  or  band-shaped  instead  of  circular  in  transverse 
section,  the  two  protoxylems  being  situated  at  the  extremi- 
ties of  the  figure.  Another  step  is  for  the  stele  to  become 
more  or  less  semilunar  in  transverse  section,  so  that  it  is  no 
longer  symmetrical  about  the  plane  passing  through  the 
protoxylems,  but  only  about  the  bisecting  plane  perpendi- 
cular to  this.  And  further  the  protoxylems  may  lose  their 
symmetrical  arrangement,  or  one  only  may  be  present,  and 
this  may  be  excentrically  placed  (Angiopteris).  We  clearly 
could  not  tell  that  such  strands  were  steles  if  we  had  no 
knowledge  of  their  connexions  and  disposition.  At  least 
as  far  as  tissue  arrangement  goes  they  may  often  be  said  to 
have  lost  those  characters  which  entitle  them  to  the  name. 
A  similar  difficulty  meets  us  in  the  case  of  the  vascular 
strands  in    many  fern   leaves.      Undoubted   steles   found  in 


216  SCIENCE  PROGRESS. 

the  petiole,  after  repeated  branchings  gradually  lose  the 
phloem  from  their  upper  sides,  and  thus  come  to  possess  the 
collateral  structure  of  the  bundle  of  a  Phanerogamic  leaf. 
On  the  other  hand  the  curved  bundle  in  the  petiole  of 
Osmunda  is  certainly  a  meristele,  if  we  may  judge  from  its 
connexion  with  the  bulky  central  cylinder  of  the  mono- 
stelic  stem,  yet  it  is  surrounded  by  a  complete  mantle  of 
phloem,  and  indeed  conforms  in  structure  to  many  true 
steles  (cf.  1 8).  We  may  probably  draw  the  same  con- 
clusion as  to  the  "  petiolar  steles  "  of  Gleicheniacese  (19). 

Similar  facts  appear  to  obtain  in  the  polystelic  genera  of 
Phanerogams,  upon  which  we  may  expect  much  new  light 
from  as  yet  unpublished  researches.  One  instance  is, 
however,  too  instructive  to  be  omitted.  A  number  of 
distinct  steles  arranged  in  a  circle  enter  the  peduncle  of 
Auricula  Delavayi  (8,  p.  304),  fuse  laterally,  and  become 
indistinguishable  from  a  monostele,  the  central  extra-stelar 
tissue  passing  over  into  pith.1  Van  Tieghem  warns  us  (10, 
p.  768)  not  to  confound  such  a  structure  formed  in  an 
essentially  polystelic  stem  with  an  essentially  monostelic 
stem.  But  if  this  sort  of  thing  may  occur,  what  guarantee 
have  we  that  an  "essentially  monostelic"  stem  is  really 
essentially  monostelic,  or,  for  the  matter  of  that,  that  an 
"  essentially  polystelic  "  stem  is  really  essentially  polystelic  ? 
If  a  stele  can  become  a  collateral  bundle  in  the  course  of  a 
shoot  system,  the  same  transformation  may  very  well  occur, 
or  a  collateral  bundle  may  become  a  stele,  in  the  course  of 
descent ;  at  least  we  are  quite  debarred  from  dogmatically 
drawing  or  denying  homologies  between  the  one  and  the 
other.  Of  course  we  can  speculate,  and  in  some  cases 
claim  a  fair  degree  of  probability  for  our  speculations, 
especially  when  we  have  a  minute  knowledge  of  all  the 
facts  in  the  anatomy  of  a  given  group,  but  since  it  is  impos- 
sible to  draw  a  sharp  line  between  a  stele  and  a  vascular 
strand  that  is  not  a  stele  we  are  clearly  not  on  very  firm 
ground.      There  is  certainly  nothing  to  surprise  us  in  this  ; 

1  A  similar  state  of  things  appears  to  obtain  in  some  of  the  Palm  roots 
investigated  by  Mr.  Cormack. 


THE  STELA R  THEORY.  217 

the  instructive  fact  is  that  "there's  such  divinity  doth 
hedge  "  a  stele — indeed  any  morphological  conception,  as  in 
almost  every  fresh  case  to  prevent  for  a  time  our  realisation 
of  the  truism  that  "  Nature  knows  no  sharp  boundaries  ". 
In  the  stelar  doctrine,  we  have,  no  doubt,  a  classification 
that  enables  us  to  perceive  a  little  more  closely  the  direc- 
tions along  which  the  various  types  of  vascular  system  in 
the  higher  plants  have  been  evolved,  and  that  after  all  is 
the  most  we  can  expect. 

DEVELOPMENTAL  EVIDENCE  BEARING  ON  THE  STATUS 

OF  THE  STELE. 

We  have  now  to  consider  the  developmental  basis 
of  the  stelar  theory.  Let  us  take  the  Phanerogams  first. 
It  is  well,  as  Dr.  Scott  (20)  has  already  pointed  out 
in  this  journal,  to  draw  a  distinction  between  de- 
velopment from  the  embryo,  and  development  of  the 
various  axes  from  their  permanently  embryonic  grow- 
ing points.  It  is  clear,  on  reflection,  that  the  former 
alone  is  comparable  to  ontogenetic  development  in  animals, 
though  it  would  be  a  mistake  to  suppose  that  the  latter  is 
not  of  importance  to  morphology.  In  the  comparatively 
few  types  of  monostelic  plants  with  the  anatomy  of  whose 
embryos  we  have  a  sufficient  acquaintance,  it  appears 
that  both  in  the  plumule  and  radicle  there  is  really  a 
clear  separation  at  the  apex  between  central  cylinder 
and  cortex  (plerome  and  periblem).  But  it  is  certainly 
open  to  doubt  whether  this  distinction,  as  Hanstein 
thought,  is  really  maintained  at  the  growing  points  of  the 
various  axes  throughout  the  life  of  the  plant.  Into  the 
history  of  the  differences  of  opinion  on  this  point  we  need 
not  enter.  The  inherent  difficulties  of  arriving  at  valid 
conclusions  from  observations  have  been  nearly  as  powerful 
as  the  subjective  causes  which  have  evidently  influenced 
the  views  of  the  observers  in  creating  the  extraordinary 
discrepancies  which  exist  between  the  various  accounts. 

The  method  employed  by  Ludwig  Koch  (21  and  22), 
who  recognised  that  the  state  of  things  at  the  growing 
point  was  likely  to  differ  at  different  epochs  of  growth,  and 


218  SCIENCE  PROGRESS. 

that  hence  conclusions  drawn  from  observation  of  a  few 
sections  could  not  be  final,  marks  a  great  advance  on 
previous  work.  Koch  claims  to  have  proved  (22),  in  Syringa 
and  Berberis,  that  the  single  layer  of  cells  immediately 
beneath  the  dermatogen,  i.e.,  the  periblem  of  earlier  ob- 
servers, divides  periclinally,  during  a  period  of  leaf  forma- 
tion, across  the  actual  apex  of  the  shoot,  thus  giving  rise  to 
three  or  four  superposed  layers  of  cells.  It  is  clear  that, 
if  this  is  the  case,  all  but  the  uppermost  of  these  layers 
must  become  part  of  the  plerome  when  the  apex  passes 
back  to  the  state  of  possessing  a  single  layered  periblem. 
But  though  our  author  has  convinced  himself  that  this 
actually  happens,  his  figures  are  not  decisive.  Most  of  the 
periclinal  divisions  which  he  shows  in  the  periblem  of  the 
Lilac  (Taf.  xvi.)  are  clearly  in  connexion  with  the  forma- 
tion of  the  leaf  rudiments.  In  no  case  are  such  divisions 
shown  across  the  actual  apex.  In  fig.  vi.  periclinal  walls  are 
drawn  in  two  periblem  cells  removed  by  one  cell  from 
the  cell-group  obviously  concerned  in  the  formation  of  a 
leaf  rudiment,  but  these  walls  are  also  removed  by  one 
or  two  cells  from  the  centre  of  the  flat  growing  point, 
and  considering  how  much  this  free  surface  is  encroached 
upon  by  the  developing-  leaves  {cf.  fig.  vii.)  it  is  not 
at  all  clear  that  the  periclinal  wall  in  question  is  not 
precociously  formed  in  a  cell  which  will  later  be  involved  in 
the  base  of  the  leaf.  Yet  this  single  periclinal  wall  is 
really  the  sole  evidence  obtainable  from  his  figures  of  the 
truth  of  Koch's  view.  Nevertheless  the  thorough  method 
of  investigation  inaugurated  by  Koch  must  sooner  or 
later  settle  the  point.  For  the  present  we  must  admit 
that  though  Hanstein's  case  is  made  out  for  a  certain  small 
number  of  plants,  the  great  majority  of  cases  which  have 
been  investigated  must  remain  doubtful.  Van  Tiegfhem 
(10,  p.  776)  does  not  definitely  commit  himself,  though  he 
implies  the  suggestion  that  Hanstein's  three  initial  layers 
are  universal  in  Phanerogams,  though  often  not  distinguish- 
able owing  to  "  enchevetrement"  of  the  layers.  But  his 
pupil  Douliot  (23)  concluded  that  there  was  a  single  apical 
cell  in    all    Gymnosperms,    and    a  plero- periblem    in    most 


THE  STELA R  THEORY.  219 

monocotyledons  and  some  dicotyledons,  while  Koch  takes 
the  view  that  there  is  a  generalised  meristem  without 
separate  layers  in  Gymnosperms  (21)  and  that  only  the 
dermatogen  is  separate  in  most  Angiosperms  (22).  So 
that  the  "triple  layer"  theory  of  Hanstein  and  Van 
Tieghem  is  accepted  by  neither  of  these  two  most  recent 
investigators  as  of  general  application,  widely  divergent  as 
are  their  views  inter  se.  Considering  that  the  theory  of 
the  direction  of  ontogeny  by  the  separation  of  different 
kinds  of  somatic  idioplasm  is  now  generally  discredited,  it 
is  difficult  to  see  what  we  gain  by  an  adherence  to  the  un- 
proved hypothesis  of  the  strict  separation  of  the  initial 
layers,  even  if  it  is  still  a  possible  hypothesis. 

In  the  root  apex  on  the  contrary  the  plerome  is  in  the 
great  majority  of  cases  sharply  separated  from  the  peri- 
blem,  but  even  this  rule  is  not  universal.  The  sharp 
separation  seems  to  be  correlated  both  in  root  and  stem 
with  the  formation  of  a  slender  compact  cylinder. 

In  Vascular  Cryptogams,  which  nearly  all  possess  either 
a  single  apical  cell  or  a  single  layer  of  initial  cells  giving 
rise  to  the  whole  of  the  tissue  of  the  axis,  there  is  of  course 
no  question  of  a  separation,  at  the  apex  itself,  of  initial 
layers. 

The  separation  of  the  young  cylinder  behind  the  actual 
growing  point  is  quite  a  distinct  question  from  its  separation 
at  the  apex.  It  is  during  the  development  of  the  cylinder 
that  we  get,  usually  at  least,  a  distinct  limit  between  it  and 
the  cortex  which  is  often  lost  in  the  adult  stem,  and  this  is 
a  point  of  great  importance. 

Long  before  the  stelar  theory  was  originated,  most  of 
the  great  anatomists,  who  laid  the  foundations  of  our  know- 
ledge of  the  histology  of  vascular  plants,  were  practically 
agreed  on  the  generality  of  this  early  separation.  This  is 
clearly  shown  in  the  terminology  employed  in  designating 
the  various  regions. 

Thus  Sanio  (24),  tracing  from  the  apex  the  development 
of  the  various  tissues,  showed  that  in  many  cases  the  young 
pith  first  became  separated  from  an  outer  zone,  and  that 
in  the  latter  the  "thickening  ring"  (really  corresponding  to 


220  SCIENCE  PROGRESS. 

Flot's  "vascular  meristem,"  i.e.,  the  ring  of  tissue  produc- 
ing the  bundle  system  plus  the  "external  conjunctive": 
shortly  became  differentiated  from  the  peripheral  zone  or 
young  cortex.  In  other  cases  {Euonymus  and  Berberis), 
the  "thickening  ring"  appeared  or  began  to  appear  before 
the  young  pith  became  separated  from  the  "  outer  zone". 
Hanstein  (25),  as  a  consequence  of  his  separation  of  the 
primary  meristem  into  Dermatogen,  Periblem  and  Plerome, 
makes  the  outer  limit  of  the  young  cylinder,  i.e.,  that 
between  periblem  and  plerome,  of  primary  rank.  Russow's 
scheme  (26),  on  the  other  hand,  drawn  from  instances  like 
those  of  Sanio's  first  group,1  in  which  the  young  pith  is  the 
first  tissue  to  become  apparent,  divides  the  young  tissue 
produced  by  the  general  Protomeristem  at  the  apex  itself 
into  Endistem  (Sanio's  young  pith)  and  Existent  (Sanio's 
"  Aussenschicht "),  the  latter  being  separated  into  Mesistem 
(Sanio's  "thickening  ring  ")  and  Peristem  or  young  cortex. 
Thus  the  limit  between  "Mesistem"  and  "Peristem'  is 
reduced  to  secondary  rank.  But  De  Bary  (14,  pp.  395-6) 
again  sums  up  clearly  in  favour  of  the  individuality  of  the 
plerome.2     As  a  matter  of  fact  the   young  pith   often  does 

1  Russow  placed  Hanstein's  best  instances,  for  example,  stem  of  Hip- 
puris,  and  Roots,  where  there  is  a  well-defined  plerome  at  the  apex  itself, 
under  the  separate  heading  of  "Axes  with  Combined  Bundles  ". 

2  The  development  of  the  pericycle  is  of  great  importance  in  this 
connexion.  Sanio  (24)  showed  in  several  cases  that  what  we  now  call  the 
pericycle  was  developed  from  the  outer  edge  of  the  "thickening  ring". 
Schmitz  (27)  confirmed  this  view  in  Berberis and  Menispermum.  Van  Tieg- 
hem,  however  (5),  based  his  conception  of  the  pericycle  entirely  on  the 
ground  of  adult  comparative  anatomy.  This  is  explicitly  stated  (p.  152)  in 
a  remark  he  made  at  the  close  of  a  "  Note  sur  le  pericycle,"  read  by 
D'Arbaumont  (28)  to  the  Botanical  Society  of  France.  D'Arbaumont  had 
endeavoured  to  show  that  the  sclerised  portions  of  the  pericycle,  capping 
the  phloems  of  the  stem  bundles  in  dicotyledons,  were  developed  in 
common  with  the  bundles  themselves  from  the  desmogen  strands,  and 
were  thus  often  separate  from  the  interfascicular  pericycle.  His  account 
of  the  development  of  the  continuous  zone  of  fibres  in  Cucurbitacese  and  in 
Berberis  is  different,  and  indicates  differences  in  the  origin  of  the  pericycle 
in  various  plants.  It  is  unfortunate  that  no  figures  are  given.  Morot  re- 
plied (29)  that  even  if  the  pericycle,  or  parts  of  it,  were  developed  dif- 
ferently in  different  plants,  that  made  no  difference  to  the  validity  or  applica- 


THE  STELA R  THEORY.  221 

become  recognisable  in  comparatively  bulky  apices  (owing 
to  the  early  ceasing  of  longitudinal  divisions,  and  the  stretch- 
ing of  its  cells),  before  the  outer  limit  of  the  young  cylinder 
is  defined.  On  the  other  hand,  in  the  slender  stems  of 
many  water  plants,  Hanstein's  scheme  applies  with  dia- 
grammatic precision,  the  outer  limit  of  the  cylinder  being 
clearly  marked  at  the  apex,  before  there  is  any  sign  of  a 
differentiation  between  pith  and  bundle  ring.  But  these 
differences  of  precocity  in  the  development  of  the  various 
regions  of  the  cylinder,  depending,  as  they  do,  upon  the 
subsequent  duration  and  size  relations  of  the  regions  are 
clearly  of  little  importance  to  morphology.  The  important 
fact  which  remains  is  the  clear  separation,  slightly  sooner, 
or  slightly  later,  of  the  young  cylinder  from  the  cortex,  in 
at  any  rate  the  vast  majority  of  cases. 

The  separation  thus  made  in  development  is,  as  a  rule, 
more  or  less  clearly  maintained  in  the  adult  stem,  though 
sometimes  it  is  lost  altogether.  There  is  the  possibility 
of  a  complete  loss  of  a  visible  boundary  between  cylinder 
and  cortex  by  the  occurrence  of  irregular  cell  divisions  in 
the  young  pericycle  and  inner  cortex,  together  with  a 
"shifting"  (Verschiebung)  of  the  original  walls  separating 
the  two  ;  unfortunately  we  do  not  know  if  this  takes  place 
in  some  cases  or  not.  But  apart  from  such  an  occurrence 
the  distinction  between  cylinder  and  cortex,  once  made,  is 
always  made,  and  the  layer  of  cells  which  once  abutted  on 
the  young  cylinder  is  still  the  phloeoterma,  not  merely 
"theoretically,"  but  in  substance  and  in  fact,  however  im- 
possible it  may  become  to  distinguish  it  from  the  surround- 
ing tissue. 

It  is  these  facts  which  form  the  real  developmental  basis 
of  the  stelar  theory. 

The  phenomena  (supposing  them  to  be  established)  of 
real  importance  in  the  opposite  sense,  would  be  the  occur- 
rence of  stems  in  which  the  external  limit  of  the  cylinder  is 
never  clear,  of  stems,  in   a   word,    which   never  possess  a 

tion  of  the  term.  The  further  pursuit  of  the  theoretical  implications  of  this 
statement  would  lead  us  into  very  deep  waters,  but  it  is  clear  that  an  ex- 
tended comparative  investigation  of  the  origin  of  the  pericycle  is  needed. 


222  SCIENCE  PROGRESS. 

cylinder  as  such.  While  we  could  not  admit  that  the  stelar 
doctrine  applied  to  such  stems,  we  should  probably  be 
forced  to  the  conclusion  if  their  vascular  system  conformed  in 
all  other  respects  to  the  monostelic  type,  that  the  plants  in 
question  were  derived  from  truly  monostelic  ancestors,  whose 
descendants  had  lost  the  limit  between  cortex  and  cylinder. 

The  Nymphseaceae,  many  of  whose  stems  contain  a 
large  number  of  "scattered"  bundles,  seem  to  furnish  us 
with  examples  of  such  plants.  Caspary  (27)  states  that 
the  bundles  are  here  developed  in  centripetal  order  :  this 
would  seem  to  indicate  an  analogy  with  those  plants 
(Piperaceae,  Begoniacese,  etc.),  which  possess  a  proper 
bundle  ring"  and  also  younger  bundles  in  the  pith,  rather 
than  with  the  monocotyledonous  type.  In  at  least  one 
member  of  the  family,  Victoria  regia,  which  possesses 
a  particularly  large  number  of  these  "scattered"  bundles, 
it  appears  that  no  well-defined  cylinder  is  visible  anywhere 
in  the  stem.1  So  here  if  anywhere  we  seem  to  have  a  real 
case  of  "astely".  We  cannot,  however,  say  the  same 
with  certainty  of  any  dicotyledonous  stem  with  a  single 
ring  of  bundles.  Nageli's  observations  (28)  indeed  led  him 
to  the  conclusion  that  the  "  cambial "  strands  were,  as 
a  rule,  developed  in  the  midst  of  a  homogeneous  ground 
tissue,  but  his  conclusions,  as  we  have  seen,  have  been 
negatived  by  most  subsequent  observers. 

Turning  to  the  vascular  cryptogams  we  find  that 
whether  monostelic  or  polystelic,  the  stele  or  steles  can  be 
traced  nearly  up  to  the  stem  apex.  The  first  formed  peri- 
clinal  walls  do  not  indeed  necessarily  mark  the  limit  of 
stelar  tissue.  They  may  cut  off  the  pith,  as  in  Equisetum 
or  mark  the  middle  of  the  cortex,  as  in  many  roots,  or 
the  outer  limit  of  the  ring  of  steles,  as  in  many  fern  stems, 
or  of  the  single  cylinder,  as  in  the  stolon  of  Nephrodium 
(10,  pp.  692  and  773-4).  Clearly  no  special  importance 
can  be  attached  to  these  walls,  and  we  certainly  can- 
not use  the  fact  that  they  mark  off  the  pith  in  Equisetum, 

1 1  owe  this  information  to  the  kindness  of  a  friend   in  telling  me  the 
results  of  some  unpublished  observations. 


THE  STELAR  THEORY.  223 

as  Van  Tieghem  does,  to  support  the  view  that  the  genus 
is  really  astelic.  This  argument  depends  on  the  assump- 
tion that  these  walls  always  separate  stelar  from  extra- 
stelar  tissue,  which  is  not  a  fact,  according  to  Van 
Tieghem  himself  (10,  p.  774),  and  further,  a  similar  line  of 
reasoning  would  tend  to  show  that  the  stems  of  a  great 
many  dicotyledons,  namely,  those  in  which  the  pith  is  the 
first  tissue  to  be  marked  off,  are  also  astelic. 

SUMMARY  OF  RESULTS. 

We  have  attempted  in  the  foregoing  pages  to  ex- 
hibit, as  clearly  as  possible,  the  bearing  of  well  ascer- 
tained facts  of  anatomy  and  development  upon  the  stelar 
theory  as  developed  by  Van  Tieghem  and  his  pupils.  We 
may  appropriately  conclude  with  an  attempt  to  summarise 
the  results  to  which  we  are  thus  led. 

We  recognise  in  the  central  cylinder  of  the  axes  of  the 
great  majority  of  the  higher  plants  an  anatomical  region  of 
the  first  rank  to  be  co-ordinated  with  the  other  great 
anatomical  regions,  the  cortex  and  the  epidermis.  The 
central  cylinder  consists  of  vascular  tissue  (xylem  and 
phloem)  and  conjunctive  tissue  (typically  parenchyma). 
In  the  bulky  typical *  cylinder  the  vascular  tissue  is  separ- 
able into  distinct  strands  corresponding  with  its  centres  (or 
rather  lines)  of  development,  and  giving  to  the  cylinder  a 
radial  symmetry  ;  the  conjunctive  of  such  a  cylinder  is 
separable  into  distinct  regions.  Typically,  also,  the  inner- 
most layer  of  cortex,  which  abuts  on  the  cylinder  is  dis- 
tinguished by  special  characters. 

Reduced  central  cylinders  are  found  in  various  stem 
structures,  especially  the  thin  stems  of  water  plants.  The 
reduction  acts  first  on  the  conjunctive,  which  may  (though 
rarely)  quite  disappear.  This  leads  to  the  coalescence  of 
the  strands  of  vascular  tissue  into  a  more  or  less  solid 
cylinder.  Such  a  reduced  cylinder  is  always  sharply  marked 
of!  from  the  cortex. 

On  the  other  hand  we  have  stems  in  which  it  is  im- 
possible   to    separate    the    conjunctive    from    the   adjacent 

1  In  Sach's  sense  of  "  most  highly  developed  ". 


224  SCIENCE  PROGRESS. 

cortical  tissue.     When  this  is  the  case  in  the  adult,  it  is  still 
often  possible  to  make  the  separation  in  the  young  stem. 

Naming  the  central  cylinder  a  stele,  we  call  all  stems 
with  a  single  cylinder  monostelic. 

Stems  in  which  we  cannot  make  the  separation  in  any 
part,  and  which  are  therefore  not  strictly  monostelic,  yet 
conform  more  or  less  to  the  monostelic  structure  in  other 
respects,  and  are  no  doubt  usually  derived  in  descent  from 
the  monostelic  type. 

Most  Ferns  and  Selaginellas,  and  two  genera  of 
Phanerogams,  while  showing  a  monostelic  structure  in 
their  hypocotyls,  possess  in  their  later  formed  stems  more 
than  one  cylinder,  each  comparable  in  structure  to  the  single 
stele  of  the  hypocotyl.  Such  stems  are  known  as  polystelic. 
The  steles  of  a  polystelic  stem  may,  however,  take  on  the 
most  various  forms,  and  lose  all  the  characters  of  the 
original  cylinder ;  several  may  even  coalesce  to  form  a 
structure  indistinguishable  from  a  single  stele.  As  this,  or 
indeed  the  converse  case  of  a  non-stelar  vascular  strand 
assuming  the  characters  of  a  stele,  may  have  happened  in 
descent  without  leaving  any  traces  of  the  transformation,  we 
are  not  justified  in  asserting  the  homology  of  all  steles  or 
denying  homology  between  steles  and  non-stelar  vascular 
strands.  Nevertheless  the  stele  is  undoubtedly  a  real  and  re- 
latively stable  type  in  the  arrangement  of  vascular  tissue,  and 
hence  the  name  represents  a  real  morphological  conception. 

The  vascular  tissue  of  a  leaf  is  arranged  in  one  or  more 
strands,  each  of  which,  bilaterally  rather  than  radially 
symmetrical,  is  called  a  schistostele  or  meristele,  representing, 
as  it  does,  a  part  only  of  the  stem  cylinder.  The  meristele 
of  a  petiole  may,  however,  simulate  a  stele.  In  most  poly- 
stelic stems  one  or  more  of  the  stem  steles  directly  enters 
the  petiole,  and  the  branches  maintain  more  or  less  of  the 
stelar  character  till  near  their  endings  in  the  lamina,  where 
they  become  indistinguishable  from  collateral  bundles. 

We  are  probably  justified  in  supposing  the  monostelic 
type  to  be  primitive  in  vascular  plants,  and  we  may  assume 
the  original  stele  to  have  been  relatively  simple.  To  the 
increase  in  bulk  of  the  stem  and  correlated  increasing  de- 


THE  STELA R  THEORY.  225 

mands  for  the  supply  of  vascular  tissue  to  leaves,  the  plant 
either  responded  by  increasing  the  bulk  of  the  stele  and 
multiplying  the  number  of  its  vascular  strands,  or  by  sub- 
stituting a  number  of  simple  steles  for  the  original  single 
one.  This  last  occurrence  happened  once  at  least  in  the 
Pteridophyta  (probably  more  often),  and  more  than  once 
among  the  Phanerogams. 

The  primordial  stele  is  represented  at  the  present  day 
by  the  single  sharply  defined  stele  of  the  embryo,  which  is 
maintained  in  the  root  and  hypocotyl,  and  which  passes  over 
in  the  stem  to  one  of  the  modern  types  of  structure, 
necessary  to  the  various  demands  of  the  leafy  shoot.  The 
arrangements  at  the  apex  of  the  latter  are  naturally  adapted 
to  form  the  particular  type  of  structure  in  question,  and 
can  in  no  case  be  considered  as  representing  an  ancestral 
form. 

BIBLIOGRAPHY. 

(1)  Ph.  van  Tieghem.     Recherches  sur  la  symetrie  de  structure 

des  plantes  vasculaires.  Introduction,  pp.  5-29.  La  Racine, 
pp.  30-314.  Annates  des  Sciences  Naturelles,  Botanique,  5 
ser.,  tome  xiii.,  1870-71. 

(2)  Van    Tieghem.       Memoire   sur    les    canaux    secreteurs    des 

plantes.     Ann.  Set.  Nat.  Bot.,  5  ser.,  tome  xvi.,  1872. 

(3)  FALKENBERG.      VergleicJiende    Untersuchnngen   fiber  d.  Ban  d. 

der  Vegctationsorgane  d.  Monocotyledonen.     Stuttgart.    1876. 

(4)  MANGIN.     Origine  et  Insertion  des  racines  adventives.    Ann. 

Set.  Nat.  Bot.,  6  ser.,  tome,  xvi.,  1882. 

(5)  VAN  TIEGHEM.     Sur  quelques  points  de  l'anatomie  des  Cucur- 

bitacees,  p.  277.  Bulletin  de  la  Societe"  Botanique  de  Fratice, 
tome  xxix.,  1882. 

(6)  Morot.    Recherches  sur  le  pericycle.    Ann.  Sci.  Nat.  Bot.,  1884. 

(7)  Van  Tieghem  et  Douliot.     (a)   Structure  de   la  tige   des 

Primeveres  nouvelles  du  Yun-nan,  p.  95.  (b)  Groupement 
des  Primeveres  d'apres  la  structure  de  leur  tige,  p.  126.  (c) 
Sur  les  tiges  a  plusieurs  cylindres  centraux,  p.  213.  Bull. 
Soc.  Bot.  France,  tome  xxxiii.,  1886. 

(8)  Van   Tieghem  et   Douliot.     Sur  la  polystelie.    Ann.  Sci. 

Nat.  Bot.,  7  ser.,  tome  iii.,  1886. 

(9)  Leclerc  du  Sablon.     Recherches  sur  la  formation  de  la  tige 

des  Fougeres.     Ann.  Sci.  Nat.  Bot.,  7  ser,,  tome  xi.,  1890. 

(10)  Van  Tieghem.    Traite  de  Botanique,  2ieme  edition,  1888-91. 


226  SCIENCE  PROGRESS. 

(il)  FLOT.      Recherches   sur   la  zone    perimedullaire.      Ann.   Sci. 
Nat.  Bot.,  7  ser.,  tome  xviii.,  1893. 

(12)  VAN  TlEGHEM.      Remarques  sur  la  structure  de   la  tige  des 

Preles.  Journal  de  Botauiqne,tome  iv.,  p.  365,  November,  1 890. 

(13)  Van  TlEGHEM.  Remarques  sur  la  structure  de  la  tige  des  Ophio- 

glossees.    Journ.  de  Bot.,  tome  iv.,  p.  405,  December,  1890. 

(14)  De  Bary.      Vergleichende  Anatomie  der  Vegetationsorgane 

der  Gefasspflanzen,  1877  (English  edition,  1884). 

(15)  STRASBURGER.     Ueber  den   Bau   und  die   Vorrichtungen  der 

Leitungsbahnen  in  den  Pflanzen.    Histologische  Beitrage  iii., 
1891. 

(16)  VAN   TlEGHEM.     Pericycle  et    Peridesme.      Journ.   de   Bot., 

tome  iv.,  p.  433,  December,  1890 

(17)  Van  TlEGHEM.     Sur  la  structure  primaire  et  les  affinites  des 

Pins.    Journ.  de  Bot.,  tome  v.,  p.  265,  etc.,  August,  1891. 

(18)  PAUL    Zenetti.       Das      Leitungssystem    im     Stamm     von 

Osmunda  regalis  L.  und  dessen  Uebergang  in  den  Blattstiel. 
Botanische  Zeitung,  April,  1895. 

(19)  Poikault.       Recherches   anatomiques  sur    les  Cryptogames 

vasculaires.     Ann.  Sci.  Nat.  Bot.,  7  ser.,  tome  xviii.,  1893. 

(20)  D.  H.  Scott.     Recent  work  on  the  Morphology  of  Tissues 

in  the  Higher  Plants.  "Science  PROGRESS,"  vol.  i., 
August,  1894. 

(21)  L.  KOCH.     Ueber  Bau  und  Wachsthum  der  Sprossspitze  der 

Phanerogamen.  Pringsheinis  Jahrbiicher  f.  zvissenschaftliche 
Botanik,  Bd.  xxii.,  1891. 

(22)  L.KOCH.    Die  vegetative  Verzweigung  der  hoheren  Gewachse. 

Pr.J.,  Bd.  xxv.,  1893. 

(23)  DOULIOT.     Recherches  sur  la  croissance  terminale  de  la  tige 

des  Phanerogames.    Ann.  Sci.  Nat.  Bot.,  7  ser.,  tome  xi.,  1890. 

(24)  San IO.       Vergleichende    Untersuchungen    iiber    die    Zusam- 

mensetzung  des  Holzkorpers.     Bot.  Zeit.,  1863. 

(25)  Hanstein.     Die  Scheitelzellgruppe,  1868. 

(26)  Russow.       Vergleichende     Untersuchungen     betreffend    die 

Histologic  .  .  .  der  Leitbiindel-Kryptogamen,  u.  s.  w. 
Memoires  de  V academic  imperiale  des  Sciences  de  St.  Pcters- 
bourgi  7  ser.,  tome  xix.,  1872. 

(27)  Schmitz.    Ueber  die  Entwicklung  d.  Sprossspitze  d.  Phanero- 

gamen.    Halle.      1874. 

(28)  D'Arbaumont.     Note    sur  le  pericycle.    Bull.    Soc.  Bot.    de 

France,  tome  xxxiii.,  p.  141,  1886. 

(29)  Morot.     Reponse   a    la   note   de  M.    D'Arbaumont   sur   le 

pericycle,  ibid.,  p.  203. 

(30)  Nageli.     Beitrage  zur  tvissenschaftliche  Botanik,  i.,  1858. 

A.  G.  Tansley. 


THE   PRESENT   POSITION  OF  THE  CELL- 
THEORY. 

PART  II. 

SINCE  I  have  shown  that  protoplasm  in  the  simplest 
form  in  which  it  is  known  to  us  may  not  be  regarded 
as  having  an  organisation  in  the  sense  in  which  that  term 
has  any  meaning,  and  since  it  is  a  waste  of  time  to  discuss 
the  use  of  the  term  when  it  has  no  meaning,  we  may  more 
profitably  turn  to  the  question  whether  protoplasm  has  a 
structure,  and  if  so,  what  kind  of  structure?  Is  it  essenti- 
ally the  same  in  all  the  kinds  of  protoplasm  which  have 
been  studied,  and  is  it  of  the  same  kind  as  the  structure  of 
tissues  and  organs  of  metazoa  or  is  it  of  a  different  kind  ? 
For  it  must  be  insisted  upon  that  one  may  deny  to  proto- 
plasm an  organisation,  in  the  proper  sense  of  the  term,  and 
yet  one  may  consistently  attribute  to  it  a  structure,  even  a 
very  complex  structure.  But  that  structure  need  not  be 
called  an  organisation,  to  do  so  is  to  confuse  two  clear 
issues.  It  is  worth  while  to  emphasise  this  point,  for  some 
people  think  it  very  inconsistent  to  affirm  that  protoplasm 
has  a  complex  structure  and  at  the  same  time  to  deny  that 
it  is  organised. 

I  conceive  that  the  view  that  protoplasm  is  composed  of 
granules,  which  are  either  biophors  or  secondary  aggregates 
of  biophors,  has  been  sufficiently  refuted  by  Butschli's  re- 
searches on  hyaline  protoplasm  already  referred  to.  The 
hyaline  pseudopodia  of  Gromia  show  no  trace  of  granules, 
not  because  the  granules  are  too  small  to  be  seen,  for  the 
highest  powers  of  the  microscope  reveal  in  the  protoplasm, 
at  the  moment  of  its  protrusion  to  form  a  pseudopodium,  a 
structure  which  is  not  granular,  namely,  an  alveolar  structure, 
and  if  granules  were  present  they  must  necessarily  be  sought 
for  in  the  alveoli  or  in  the  alveolar  walls.  But  they  are  to 
be  found  in  neither,  so  it  may  be  affirmed  that  in  the 
simplest    form    of    protoplasm    there     are    no    granules,    a 

circumstance  which  deprives  the  theory  of  biophors  of  much 

16 


228  SCIENCE  PROGRESS. 

of  its  weight.  Of  course  it  may  be  objected  that  the 
alveolar  walls  and  contents  may  be  composed  of  biophors 
so  small  as  to  defy  detection  ;  such  an  objection  must  be 
defended  on  theoretical  grounds,  and  I  will  deal  with  it 
presently  ;  just  now  I  will  confine  myself  to  the  considera- 
tion of  the  visible  structure  of  protoplasm. 

After  rejecting  the  granular  theory  we  have  a  choice  of 
several  others  ;  the  fibrillar  theory,  the  reticular  theory,  and 
the  alveolar  theory  of  Biitschli.  It  would  take  too  long  for 
me  to  examine  these  several  theories  in  detail  ;  it  has 
already  been  done  by  Biitschli  (loc.  ciL,  p.  177),  and  still 
more  recently  by  Yves  Delage,1  if  I  were  to  undertake  the 
task  I  should  only  give  a  resume  of  their  arguments. 
For  my  own  part  I  am  strongly  inclined  in  favour  of  Biit- 
schli's  "  Wabenlehre  ". 

For  some  reason  or  other  Biitschli's  account  of  the 
structure  of  protoplasm  has  not,  to  use  a  common  ex- 
pression, "  caught  on  ".  Possibly  because  it  was  published 
at  a  time  when  men's  minds  were  occupied  with  the  more 
alluring  prospect  offered  by  the  granular  theory  of  proto- 
plasm, with  all  its  delusive  hopes  of  an  explanation  by  means 
of  biophors,  and  primary  organisation  of  the  phenomena 
of  heredity,  and  of  all  the  vital  processes.  Possibly  also 
because  Biitschli  himself  pushed  the  analogy  between  micro- 
scopic foams  and  protoplasmic  structure  too  far.  But  if 
his  theoretical  considerations  are  put  aside,  there  is  a  great 
deal  to  be  said  for  his  fundamental  views.  The  alveolar 
structure  which  he  describes  may  be  demonstrated  in  many 
various  forms  of  protoplasm.  It  is  particularly  obvious  in 
Pelomyxa,  in  which  form  the  larger  vacuoles  serve  admir- 
ably as  a  contrast  between  the  finer  alveolar  structure  which 
he  claims  to  be  common  to  all  protoplasm  and  the  grosser 
vacuolar  structure  which  is  often  mistaken  for  it.  I  have 
myself  identified  the  alveolar  structure  in  a  considerable 
variety  of  protozoa,  and  in  a  number  of  tissue  cells,  and  I 
have  succeeded  in  making  Biitschli's  artificial  amoebae,  and  am 

1  Yves  Delage,  La  Structure  du  Protoplasma  et  les  Theories  sur 
V Heredite  et  les  grands  problems  de  la  Biologie  generate.  Paris :  C. 
Reinevald  et  Cie,  1895. 


THE  PRESENT  POSITION  OF  CELL-THEORY.     229 

convinced  of  the  close  analogy  in  structure  between  the 
artifact  and  the  natural  product.  The  resemblance  between 
the  two  is  exact,  and  it  is  astonishing.  The  optical  char- 
acters of  the  artificial  product  are  explained,  on  physical 
grounds,  as  the  outcome  of  a  certain  structure,  namely,  an 
alveolar  structure.  The  identical  optical  characters  of  pro- 
toplasm may  surely  be  explained  on  the  same  grounds.  It 
is  not  pushing  analogy  too  far  to  say  that  identical  optical 
characters  are  the  result  of  identity  of  structure.  The 
analogy  is  somewhat  strained  when  it  is  sought  to  prove 
that  the  identity  of  the  streaming  movements  in  the  arti- 
ficial  product  with  those  in  protoplasm  are  attributable  to 
the  same  physical  causes.  The  chemical  constitution  of 
the.  two  bodies  is  so  different  that  the  phenomena  observed 
might  be  regarded  as  secondary.  Nor  is  the  identity 
absolute,  for  Biitschli  himself  points  out  that  the  induced 
currents  in  the  surrounding  medium  take  place  in  the  re- 
verse sense  in  an  amoeba  to  what  they  do  in  the  case  of 
the  microscopic  foam.  I  cannot  think  that  the  criticism  of  O. 
Hertwig  invalidates  Biitschli's  theory  seriously.  Hertwig 
says  that  lamellae  of  oil  consist  of  a  fluid  which  is  not 
miscible  with  water.  If  the  comparison  between  the 
structure  of  an  emulsion  and  the  structure  of  protoplasm 
depends  on  something  more  than  a  superficial  resemblance, 
then  the  lamellae  of  plasma  which  are  compared  with  the 
lamellae  of  oil  must  consist  of  a  solution  of  albumen 
or  of  a  fluid  albumen.  But  a  solution  of  albumen  is 
miscible  with  water,  and  therefore  it  would  mix  with  the 
contents  of  the  alveoli :  emulsions  of  albumen  must  be  formed 
with  air,  not  with  water.  To  this  Biitschli  answered  that 
the  framework  of  plasma  consists  of  a  fluid  composed  of  a 
combination  of  an  albumen  and  a  fatty  acid,  which  was 
therefore  not  miscible  in  water.  Another  obvious  answer 
is  that  living  plasma  is  not  a  simple  albuminous  solution, 
for  if  it  were  most  protozoa  could  not  exist,  they  would 
immediately  dissolve  in  the  water  in  which  they  live. 
Whether  a  fatty  acid  exists  in  combination  with  the  plasma 
or  not,  there  is  something  in  the  constitution  of  living- 
plasma  which  differentiates  it  from  albumen,  for  it  does  not 


23o  SCIENCE  PROGRESS. 

dissolve  in  water  ;  dead  plasma  on  the  other  hand  becomes 
albumen  and  dissolves  speedily.  What  that  something  is 
I  do  not  venture  to  suggest  ;  could  we  ascertain  what  it  is, 
no  doubt  we  should  have  discovered  the  solution  to  the 
riddle  of  life.  Hertwig  says  that  the  structural  elements  of 
protoplasm,  be  they  filaments,  or  reticular,  or  lamellae,  or 
alveoli,  or  granules,  or  what  else,  have  a  fixed  state  of 
aggregation.  Protoplasm  is  no  mixture  of  two  immiscible 
substances  such  as  water  and  oil,  but  consists  of  a  union  of 
fixed  organic  material  particles  with  abundant  water.  This 
is  but  a  verbal  statement  of  the  facts  and  is  no  explanation, 
but  he  adopts  later  on  {Joe.  tit.,  p.  49)  Nageli's  micellar 
theory  as  an  explanation.  No  doubt  it  is  the  best  explana- 
tion possible,  but  it  again  does  not  give  more  than  a  verbal 
explanation  of  the  remarkable  and  fundamental  phenomenon 
that  protoplasm,  be  its  structure  what  it  may,  does  not  when 
alive  dissolve  in  water,  but  when  dead  it  becomes  some- 
thing else  which  readily  dissolves,  provided  of  course  that  it 
is  not  killed  by  means  which  coagulate  the  albumens  into 
which  it  is  converted  at  death. 

I  shall  recur  again  to  the  micellar  theory,  for  the  pre- 
sent purpose  it  is  sufficient  to  say  that  it  is  not  inconsistent 
with  Biitschli's  "  Wabenlehre,"1  and  might  even  be  pressed 
into  service  to  explain  why  the  plasma  does  not  mix  with 
the  watery  alveolar  contents  without  the  necessity  of  calling 
fatty  acids  to  aid. 

Supported  by  these  considerations,  and  by  a  considerable 
mass  of  objective  evidence,  I  venture  to  think  that  Btitschli 

1  Biitschli  criticises  the  micellar  theory  and  the  analogous  theory  of 
"inotagmas"  put  forth  by  Engelmann.  He  does  not  accept  either,  but 
does  not  give  in  their  place  any  theory  of  the  ultimate  compositions  of  the 
substances  which  form  the  alveolar  framework  and  contents,  except  that 
(p.  309)  he  says,  "  a  series  of  reflections  .  .  .  led  me  to  suppose  .  .  .  that 
the  chemical  basis  of  the  framework  substance  must  be  formed  by  a  body 
which  has  arisen  from  a  combination  of  albuminoid  and  fatty  acid  mole- 
cules." Such  a  combination  must  mean  the  formation  of  a  chemical  unit 
of  a  higher  order  than  the  molecules  which  enter  into  its  composition,  and 
for  my  purposes  such  a  chemical  unit  is  a  micella.  In  this  limited  sense 
the  acceptance  of  a  micellar  structure  is  not  incongruous  with  the  "  Wa- 
benlehre ". 


THE  PRESENT  POSITION  OF  CELL-THEORY.      231 

has  given  a  true  account  of  the  minute  structure  of  proto- 
plasm, so  far  as  it  can  at  present  be  determined  by  optical 
means.  And  I  even  venture  to  prophecy  that  when  the 
history  of  the  biological  work  of  this  half  century  comes  to 
be  written  some  half  century  hence,  the  theories  of  biophors 
and  plasomes  and  the  such  like  will  have  merely  a  historical 
interest,  whilst  the  work  of  Biitschli  will  be  regarded  as  the 
most  sagacious  and  far-sighted  contribution  of  our  time  to 
this  momentous  question.  In  saying  this  I  do  not  wish 
to  declare  my  adhesion  to  the  more  theoretical  part  of 
Biitschlis  work,  but  only  to  his  account  of  the  microscopic 
structure  of  protoplasm. 

Even  if  one  were  to  accept  his  explanation  of  the 
streaming  movements  there  would  remain  all  the  other 
phenomena  of  life  to  be  accounted  for,  and  they  are  inex- 
plicable on  the  visible  structure  of  protoplasm,  even  if  it  be 
an  alveolar  structure. 

Underlying  the  visible  structure  then  there  must  be  an 
invisible  structure,  which  is  the  cause  of  the  phenomena. 
This  admission  once  made,  the  claims  of  the  rival  theories 
of  biophors,  plasomes,  plastidules  and  what  not,  again  press 
themselves  on  our  attention.  Now  it  is  to  be  remarked 
that  the  most  cautious  and  thoughtful  theorists  do  not  claim 
that  their  hypothetical  units  are  an  explanation  of  life. 
Weismann  categorically  denies  that  his  theory  of  the  germ 
plasm  is  a  theory  of  life,  it  is  only  a  theory  of  heredity,  but 
he  goes  so  far  as  to  suggest  that  a  workable  explanation  of 
the  more  complicated  vital  phenomena  may  be  the  surest 
indication  of  the  path  which  will  lead  to  an  explanation  of 
the  more  simple  (loc.  ciL,  p.  21). 

Others,  however,  are  not  so  cautious,  and  in  any  case 
there  is  this  feature  common  to  all,  that  they  aver  on  the 
one  hand  that  vital  processes  are  so  complicated  that  they 
cannot  be  explained  by  a  physico-chemical  theory  of  the 
constitution  of  protoplasm,  and  that  therefore  we  must 
assume  the  existence  of  ultimate  vital  units  or  biophors  : 
on  the  other  hand,  after  endowing  these  biophors  with  all 
the  attributes  of  life,  they  say  that  they  have  a  comparatively 
simple  molecular  constitution   upon  which  the  phenomena 


232  SCIENCE  PROGRESS. 

which  they  exhibit  depend.  In  fact  they  describe  essenti- 
ally similar  functions  in  biophors  and  in  cells,  but  they 
allow  a  physico-chemical  explanation  in  one  case  and 
disallow  it  in  the  other.  This  contradiction  has  been 
noticed  by  others,  and  it  has  never  been  satisfactorily 
explained  away.  Whitman  draws  attention  to  it,  and 
observes  that  no  one,  as  far  as  he  knows,  has  looked  upon 
the  unit  as  anything  more  than  the  seat  of  the  mystery. 
This  is  true,  but  it  is  no  reason  for  putting"  the  mystery  in 
a  small  bag  instead  of  a  big  one.  He  defends  the  theories 
of  smaller  units,  however,  by  saying  that  they  have  ex- 
tended our  knowledge  of  organic  mechanism  {Joe.  cit., 
prefatory  note,  p.  vi.).  This  again  I  believe  to  be  true, 
but  not  quite  in  the  sense  in  which  Whitman  apparently 
means  it  to  be.  The  theories  of  minute  independent  vital 
units  have,  I  believe,  led  many  on  the  wrong  track  as 
regards  vital  mechanism  ;  the  attacks  on  such  theories  are 
leading  to  a  considerable  extension  of  our  knowledge  in 
this  direction.  The  ultimate  vital  units  confessedly  do  not 
remove  the  mystery ;  ultimately  the  explanation  of  life 
must  be  a  chemico-physical  one  ;  there  is  no  alternative 
but  a  vitalistic  theory,  and  this  is  not  admissible  in  science. 
The  strongest  ground,  viz.,  the  granular  hypothesis,  for 
assuming  the  presence  of  vital  units  is  removed  by  the 
observed  constitution  of  hyaline  protoplasm,  and  finally 
none  of  the  assumed  aggregates  of  units  which  are  admitted 
to  be  visible,  are  identified  with  various  sorts  of  granules 
and  considered  to  constitute  units  of  a  higher  order,  have 
ever  been  shown  to  be  capable  of  leading  an  independent 
existence. 

On  the  other  hand  there  is  a  oeneral  consensus  of 
opinion  that  protoplasm  is  not  a  simple  organic  compound. 
Its  unit  is  not  the  molecule,  but  an  aggregate  of  molecules 
forming  a  unit  of  a  higher  order  to  which  the  molecule 
stands  in  the  same  relation  as  the  atom  does  to  the  mole- 
cule. It  is  also  admitted  that  these  molecular  aggregates 
may  exist  in  many  different  kinds  in  protoplasm.  Such  a 
conception  is  absolutely  necessary  for  the  explanation  of 
the  most  simple  properties  of  organic  bodies,  for  example, 


THE  PRESENT  POSITION  OF  CELL-THEORY.     233 

their  optical  properties  and  the  imbibition  of  water.  But  it 
is  a  physico-chemical  conception,  and  the  molecular  aggre- 
gate need  not  and  should  not  be  endowed  with  independent 
vital  powers.  Such  a  molecular  aggregate  is  the  micella. 
In  accepting  the  micella  one  may  attribute  any  amount  of 
complexity  to  protoplasmic  structure  without  for  a  moment 
admitting  that  it  is  a  cono-eries  of  elementary  organisms. 
Nor  need  we  admit  all  the  theories  which  Nageli  has  tried 
to  establish  as  the  necessary  consequences  of  the  assumption 
that  there  are  such  things  as  combinations  of  polyatomic 
molecules  into  groups  of  a  higher  order.  As  I  have  already 
said,  it  was  pointed  out  by  von  Sachs  that  even  in  the 
region  of  pure  chemistry  it  is  necessary  to  assume  that  polya- 
tomic molecules  are  grouped  into  closer  molecular  unions, 
thus  giving  rise  to  chemical  properties  which  did  not  belong- 
to  the  individual  molecules.  But  in  the  region  of  pure 
chemistry  such  a  grouping  is  not  called  an  organisation, 
nor  is  there  any  reason  why  it  should  be  called  an  organisa- 
tion in  the  present  case.  Let  us  be  perfectly  definite  and 
say  that  by  a  micella  we  mean  a  combination  of  polyatomic 
molecules  into  closer  union  to  form  a  group  ;  nothing  more, 
except  in  so  far  as  we  may  reason  on  chemico-physical 
grounds  as  to  the  behaviour  of  such  groups  and  their 
relations  inter  se.  For  instance  (I  am  quoting  from  O. 
Hertwig's  summary  of  this  part  of  the  micellar  theory)  : 
"The  micellae  exert  an  attraction  both  on  water  and  on  one 
another,  whereby  the  phenomena  of  swelling  may  be  ex- 
explained.  In  a  dry  organic  body  the  micellae  lie  close  to 
one  another,  separated  only  by  exiguous  envelopes  of 
water  :  these  latter  enlarge  considerably  during  imbibition, 
since  the  attractive  forces  between  the  micellae  and  water 
are  at  first  greater  than  between  the  micellae  themselves. 
The  micellae  are  separated  from  one  another  by  the  imbibed 
water  as  it  were  by  a  wedge  ;  but  an  organised  body  does  not 
arrive  at  a  condition  of  solution,  since  the  attraction  of  the 
micellae  for  water  diminishes  in  the  course  of  their  separa- 
tion from  one  another,  at  a  greater  rate  than  the  attraction 
of  the  micellae  for  one  another,  and  therefore,  when  the 
watery  envelopes  have  attained  a  certain  size,  a  condition 


234  SCIENCE  PROGRESS. 

of  equilibrium,  the  limit  of  imbibition  is  reached."  And 
also:  "Since  particles  of  water  may  be  held  fast  on  the 
surfaces  of  the  micellae  by  molecular  attraction,  so  also 
other  matters  (lime  and  siliceous  salts,  colouring  matters, 
gelatin  compounds,  etc.)  may  be  deposited  on  them  after 
they  have  been  taken  into  the  organic  body  in  a  state  of 
solution  ".  So  far  as  my  physical  knowledge  enables  me  to 
form  a  judgment,  attributes  such  as  these  may  justifiably  be 
ascribed  to  micellse  on  purely  physical  grounds  and  their 
importance  can  hardly  be  overestimated,  since  the  last 
passage  quoted  affords  a  hint  as  to  the  nature  of  the  essen- 
tially vital  process  of  assimilation.  It  is  not  my  business 
now  to  develop  a  complete  theory  ;  I  doubt  indeed  whether 
a  complete  theory  is  possible  in  the  present  state  of  our 
knowledge.  I  have  done  sufficient  for  present  purposes  if 
I  have  succeeded  in  indicating  what  ideas  we  may  justifiably 
hold  on  the  subject  of  protoplasmic  structure,  and  I  believe 
that  I  have  given  some  good  grounds  for  justification  of  the 
views  that ;  (i)  the  ultimate  visible  structure  of  protoplasm 
is  an  alveolar  structure  ;  (2)  that  the  invisible  structure  of 
protoplasm  is  a  "micellar"  structure  in  the  sense  defined 
above. 

But  before  I  proceed  I  must  enter  a  caveat  against 
being  considered  as  an  adherent  of  the  micellar  theory  of 
Nageli.  I  cannot  enter  here  into  my  reasons,  but  I  may 
say  that  the  further  theories  which  Nageli  assumes  to 
be  the  necessary  consequences  of  the  existence  of  micellae, 
do  not  appear  to  me  to  be  necessary  consequences  at  all  ; 
indeed  I  part  company  with  him  at  once  when  I  express  my 
conviction  that  the  hypothesis  of  a  micellar  structure  is 
compatible  with  the  alveolar  structure  described  by 
Butschli.1 

1  Since  the  above  argument  was  first  written  out  the  work  of  Yves 
Delage  has  come  into  my  hands.  It  is  most  gratifying  to  find  that  the 
opinions  of  so  distinguished  an  author  accord  so  exactly  with  my  own.  The 
reader  who  finds  my  argument  involved  and  laborious  may  turn  with  profit 
to  Delage's  book,  in  which  he  will  find  a  lucidity  of  expression  and  a 
precision  in  argument  which  I  can  only  envy  without  hoping  to  imitate.  It 
is  worth  while  quoting  the  following  passages  here:   "On  peut   accorder 


THE  PRESENT  POSITION  OF  CELL-THEORY.     235 

I  may  now  anticipate  the  objection  which  is  certain  to 
be  raised  that  the  visible  and  invisible  structure  which  I 
assign  to  protoplasm  is  utterly  inadequate  to  explain  the 
phenomena  of  life.  It  is  inadequate  and  it  is  intended  to 
be  inadequate.  Were  I  to  pretend  that  it  is  adequate  I 
should  be  running  counter  to  all  the  lessons  taught  by  our 
experience  of  living  things.  The  structure  which  I  have 
assigned  to  protoplasm  applies  particularly  to  that  simplest 
known  form  of  it  which  we  rarely  meet  with,  but  which  we 
do  meet  with  in  exceptional  cases,  for  instance  in  the  pseudo- 
podia  of  Gromia  dujardini.  But  separate  a  protoplasmic 
corpuscle  formed  by  the  thickenings  of  the  thread-like  pseu- 
dopodia  of  this  species  from  the  rest  of  the  animal ;  the  cor- 
puscle separated  is  not  any  longer  capable  of  an  indepen- 
dent existence,  it  soon  perishes,  it  has  all  the  structure 
which  I  have  described,  but  it  is  not  capable  of  in- 
dependent life.  Clearly  then  life  is  not  the  outcome  of  this 
structure,  though  the  structure  may  play  its  part,  and  no 
unimportant  part  in  the  life  processes. 

When  I  have  been  speaking  of  protoplasm  I  have 
obviously  been  confining  my  attention  to  that  form  of  it 
which  is  now  generally  distinguished  under  the  name  of 
Cytoplasm.  Cytoplasm  taken  by  itself  is  not  living  matter 
in  the  sense  that  it  is  capable  by  itself  of  maintaining  an 
independent  existence.  The  experiments  of  Nussbaum,1  of 
A.  Gruber  and  Verworn,  confirmed  by  other  observers,  have 

a  l'auteur  (Nageli)  ses  Micelles.  Leur  constitution,  leurs  proprietes  n'ont 
rien  que  de  tres  admissible.  Bien  que  leur  mode  de  generation  ne  soit 
guere  probable,  il  n'y  a  aucune  raison  positive  pour  le  repousser.  Mais 
l'arrangement  des  micelles  et  la  structure  de  l'idioplasma  sont  invraisem- 
blables  au  plus  haut  point.  Nous  avons  demontre,  au  cours  de  notre 
expose,  que  cet  arrangement  n'est  pas  de  tout,  com  me  l'auteur  l'avance,  le 
resultat  necessaire  du  seul  jeu  des  forces  moleculaires  initiates  ce  n'est 
qu'a  grand  renfort  d' hypotheses  etagees  l'un  sur  les  autres  qu'il  arrive  a 
faire  disposer  les  Micelles  en  Files,  les  Files  en  Faisceaux,  les  Faisceaux  en 
Cordons  et  les  Cordons  en  un  Reseau  repandu  dans  tout  l'organisme." 

1  It  was  Nussbaum  who  first  introduced  the  method  of  dividing  in- 
fusoria by  artificial  means,  and  the  credit  of  having  devised  this  very  useful 
class  of  experiment  belongs  to  him.  In  my  previous  article  I  inadvertently 
assign  it  to  Gruber. 


236  SCIENCE  PROGRESS. 

shown  that  pieces  of  cytoplasm  cut  off  from  the  remainder 
of  a  protozoon  are  incapable  of  maintaining  life  and  soon 
perish.  If,  on  the  other  hand,  a  fragment  of  cytoplasm 
similarly  cut  off  contains  nuclear  matter,  it  is  shown  to  con- 
tain the  attributes  necessary  to  life,  for  the  fragment  does 
not  perish  but  reconstitutes  itself  and  becomes  an  inde- 
dependent  living  being.  The  converse  also  holds  good. 
A  nucleus  or  a  fragment  of  a  nucleus  isolated  from  a 
protozoon,  is  incapable  of  life  and  perishes.  But  a  nucleus 
or  a  fragment  of  a  nucleus  in  conjunction  with  a  fragment 
of  cytoplasm  is  capable  of  life  and  constitutes  an  indepen- 
dent living  being.  The  reasonable  inference  is  that  cyto- 
plasm plus  nuclear  matter  is  indispensable  for  the  per- 
formance of  vital  functions. 

Now  cytoplasm  plus  nuclear  matter  constitutes  a  cell. 

I  have  elsewhere  discussed  at  some  length  the  definition 
of  a  cell,1  and  I  have  defined  it  as  a  corpuscle  of  protoplasm 
which  contains  nuclein.  In  the  present  state  of  our  know- 
ledge this  definition  seems  the  only  one  possible.  The  cell 
then  consists  of  two  essential  substances,  cytoplasm  and  a 
substance  which  is  different  from  cytoplasm,  both  structurally 
and  in  chemical  constitution,  namely,  nuclein.  In  a  great 
majority  of  cells  other  substances  are  present  which  are 
different  from  both  of  these.  Such  substances  are  the 
centrosomes,  that  modification  of  cytoplasm  which  is  called 
archoplasm,  amylum  and  aleurone  grains  and  so  forth.  As 
far  as  we  know,  however,  these  substances  are  not  essential 
to  life,  but  are  secondary  products  characteristic  of  dif- 
ferentiated cells.  Recent  researches  on  the  structure  of 
Bacteria  and  Oscillaria  justify  the  assertion  that  cells  exist 
in  which  these  substances  are  absent.  We  know  next  to 
nothing  about  the  presence  or  absence  of  centrosomes  and 
archoplasm  in  the  Protozoa,  and  it  may  be  that  further 
investigation  will  lead  us  to  the  conviction  that  these  two 
are  as  essential  to  the  life  of  these  forms  as  the  presence  of 
cytoplasm   and   nuclein.      Maybe  not  ;  in  any  case  it  does 

1  Quarterly   Journal  of  Microscopical  Science,    vol.  xxxviii.,    p.    137, 
1895. 


THE  PRESENT  POSITION  OF  CELL-THEORY.     237 

not  matter  for  present  purposes.  It  is  sufficient  to  know 
that  two  substances,  cytoplasm  and  nuclein,  must  be  brought 
together  or  life  cannot  exist,  and  that  it  does  exist  in 
organisms  in  which  these  substances,  and  these  only,  can  be 
detected,  viz.,  in  Bacteria.  This  statement  may  appear  some- 
what hazardous,  seeing  that  the  presence  of  a  nucleus  is 
denied  in  several  living  beings,  in  bacteria,  for  instance,  and 
in  yeast.  A  nucleus  in  the  sense  of  a  centralised  body  is 
certainly  absent  in  these  and  in  many  other  forms,  but 
Biitschli  has  demonstrated  the  presence  of  nuclein  in 
Oscillaria  in  Bacterium  lineola.  As  for  Saccharomyces  it 
undoubtedly  contains  nuclein,  for  Raum  has  prepared  it 
from  yeast  cells,  and  the  most  recent  observer,  Macallum,1 
is  of  the  opinion  that  the  nuclein  is  distributed  through  the 
cytoplasm  but  also  aggregated  in  the  so-called  granules  of 
Raum. 

The  statement  therefore  can  scarcely  be  called  hazardous, 
and  it  is  really  warranted  by  the  facts  at  our  disposal,  for 
the  more  carefully  that  researches  are  made,  and  the  more 
delicate  the  methods  of  investigations  employed,  the  more 
is  the  presence  of  nuclein  demonstrated  where  it  was  not 
previously  supposed  to  exist. 

Macallum's  paper,  by  the  way,  is  of  great  interest,  for  he 
shows  that  nuclein  is  essentially  the  iron-holding  substance 
in  cells.  Knowing  as  we  do  the  close  connection  there  is 
between  the  presence  of  iron  and  the  due  performance  of 
the  vital  processes,  this  observation  opens  up  a  fruitful 
source  of  inquiry  as  to  the  dependence  of  life  on  chemical 
processes. 

Throughout  this  argument  I  have  tried  to  stick  to  the 
rule  of  drawing  legitimate  inferences  from  observed  facts 
without  wandering  into  the  obscure  regions  of  hypothesis. 
If  I  have  been  successful  and  have  fairly  stated  the  facts, 
and  have  drawn  legitimate  inferences,  the  conclusion  which 
I  come  to  must  be   admitted  to  be  of  considerable  weight. 

1  A.  B.  Macallum,  "On  the  distribution  of  Assimilated  Iron  Com- 
pounds, other  than  Haemoglobin  and  Haematins,  in  Animal  and  Vegetable 
Cells,"  Quart.  Jour.  Mir.  Sri.,  vol.  xxxviii.,  pp.  175-274,  1895. 


238  SCIENCE  PROGRESS. 

The  conclusion  is  this  :  that  life  is  possible  only  when  two 
(or  more)  substances  of  complex  chemical  constitution  are 
brought  together,  and  that  when  these  two  (or  more)  substances 
ai'e  brought  together  we  have  before  us  a  cell.  The  cell  there- 
fore is  the  vital  unit  /car'  e^o^V.  The  component  parts  of 
the  cell  are  not  vital  units,  for  by  themselves  they  are  in- 
capable of  life;  they  are  the  auxiliaries,  the  indispensable 
auxiliaries  of  life,  but  they  are  not  themselves  living. 

This  is  not  a  theory  of  life,  and  it  does  not  pretend  to 
be  one.  It  is  the  generalisation  which  the  facts  seem  to 
warrant,  and  if  it  be  true,  as  I  believe  it  must  be  true,  it  is 
entirely  inconsistent  with  the  whole  group  of  theories  based 
upon  hypothetical  biophors,  gemmules,  plasomes,  physio- 
logical units,  plastidules  et  hoc  genus  omne.  Those  theories 
are  false.  And  the  cell  theory  is  not  inadequate,  but  it  is 
the  only  theory  which  our  knowledge  of  structure  and  of 
life  processes  permits  us  to  adopt,  at  least  if  we  confine 
ourselves  to  that  part  of  it  which  is  essential,  namely,  that 
there  is  one  general  principle  for  the  formation  all  tissues, 
animal  and  vegetable,  and  that  principle  is  the  formation  of 
cells. 

Cells  are  the  ultimate  vital  units,  though  they  are  not 
the  ultimate  structural  units  ;  they  are  the  Lebenstrager,  or 
biophors,  and  there  are  no  living  individuals  lower  than 
cells. 

As  I  have  made  an  effort  to  stick  to  facts  and  have 
slighted  hypotheses,  I  shall  doubtless  incur  the  profound 
contempt  of  those  superior  persons  who  find  no  mental 
repose  in  things  which  can  be  clearly  apprehended,  but 
must  leave  the  material  support  of  earth  and  seek  for  rest  on 
the  unsubstantial  pillows  of  cloudland.  They  will  have 
abundant  scope  for  exercising  their  contempt,  for  my  con- 
clusion explains  nothing,  and  gives  no  clue  to  the  problems 
of  heredity. 

As  I  have  said  in  the  earlier  part  of  this  essay,  I  have 
no  intention  to  discuss  here  the  complicated  problems  which 
are  involved  in  the  question  of  heredity.  I  take  my  stand 
on  the  position  from  which  I  started,  namely,  that  if  minute 


THE  PRESENT  POSITION  OF  CELL-THEORY.     239 

vital  elements  occur  at  all,  those  same  elements  which  make 
life  possible  and  control  assimilation  and  growth  must  also 
be  the  agents  in  bringing  about  the  phenomena  of  heredity. 
I  have  shown  that  minute  vital  elements  smaller  than 
cells  cannot  be  believed  to  exist,  and  it  is  clear  that  the 
phenomena  of  heredity  cannot  be  explained  by  things 
which  have  no  existence.  This  is  a  sufficient  answer  to 
those  who  would  say  that  the  phenomena  of  heredity  are 
such  that  we  must  make  use  of  a  hypothesis  of  minute 
vital  elements,  which  are  at  once  the  bearers  of  the  vital 
qualities  and  the  bearers  of  the  heritable  qualities  (the  his- 
toric properties  if  the  expression  is  preferred)  of  protoplasm. 
It  is  not  true  that  a  theory  of  heredity  is  impossible  unless 
such  elements  are  postulated.  Delage  has  brought  forward 
a  theory  of  heredity  which  discards  altogether  the  use  of 
hypothetical  biophors.  I  pass  no  criticism  on  his  theory, 
favourable  or  unfavourable,  but  call  attention  to  it  merely 
for  the  purpose  of  showing  that  a  theory  without  biophors 
is  possible.  It  is  no  argument  to  say  that  the  theories 
based  on  ultimate  vital  units  have  largely  extended  our 
knowledge  of  heredity.  The  Ptolemaic  system  of  astronomy 
largely  extended  men's  knowledge  of  the  movements  of 
the  heavenly  bodies,  but  it  was  not  on  that  account  a  true 
theory. 

Moreover,  it  will  be  hardly  fair  to  twit  me  with  the 
fact  that  I  renounce,  for  the  present,  an  attempt  to  explain 
the  most  complicated  manifestations  of  life,  for  this  is  only 
an  essay,  and  makes  no  pretence  to  be  the  development  of 
a  doctrine. 

It  is  not  my  present  intention  to  frame  hypotheses,  not 
because  I  undervalue  the  use  of  hypothesis,  but  because  I 
regard  the  first  necessary  step  to  be  the  formation  of  ideas 
appropriate  to  the  facts. 

Dr.  Whitman  has  recently  written  quite  a  nice  little 
lecture  on  the  subject  of  fact  and  theory,  and  has  directed 
it  against  myself  in  particular,  winding  up  with  a  trenchant 
paragraph  to  the  effect  that  the  claim  to  a  monopoly  of 
fact  reflects  an  arrogance  which  seems  to  be  epidemic. 
This    homily    is    fortified    by    quotations   from    von    Baer, 


240  SCIENCE  PROGRESS. 

Goethe,    Huxley    and    Whewell.       Now    I    never    claimed 
a   monopoly   of  fact,  but  that  facts  should   receive  a  due 
share  of  recognition.      Mutual   service,   as  Whitman   says, 
is  the  principle  which  ties  theory  and  fact  together  ;  quite 
so,  but  when  theory   runs   altogether  away   from   fact,  the 
mutual   service   is   wanting.      Fact   is  a   slow  servitor,  and 
drags  heavily  on  the  impatient  feet  of  theory.      The  quota- 
tions from  Goethe  and  Huxley  do  not  lend  support  to  the 
practice  of  making  hypotheses,  rather  the  contrary.      "Ex- 
perience. Reflection,  Inference  "  is  an  excellent  motto,  but 
inference  does  not  mean  making  hypotheses,  nor  yet  does 
the   necessary   process  of  generalisation   and   classification 
which  Huxley  recommends.      The  passage  quoted  from  the 
last-named  author  condemns  the   mere  cataloguing  of  facts 
under  the  name  of  Science,  but  it  does  not  countenance  the 
reckless  use  of  theory.      As  for  Whewell's  aphorism,  let  me 
commend   to   Whitman   a   study  of  what  that  author  says 
with  regard  to   the   failure   of  the  Greek  schools  of  philo- 
sophy.    They  did  not  fail,  he  says,  because  they  neglected 
facts  ;  the  Aristotelian  school  may  be  held  to  have  surpassed 
the  moderns  in  its  appreciation  of  the  value  of  facts.     The 
Greeks  certainly  did  not  fail  for  want  of  boldness  in  theor- 
ising, nor  for  want  of  acuteness,  of  ingenuity  and  power  of 
close  and  distinct   reasoning.      Nevertheless   with   all  help 
from   the   twin-service  of  fact  and  theory  their  philosophy 
was  a  failure,  and  why  ?      Because,  as  Whewell  points  out, 
their  ideas   were  not  distinct  and  appropriate  to  the  facts. 
May  not  the  same  thing  be  said  of  many  of  the  theories  of 
cell  life  and  of  heredity  which  have  been  so  much  in  vogue 
in  the  last  few  years  ?      It  was  my  object  when  I  wrote  on 
Epigenesis  and  Evolution   to   show   that  some  ideas  then 
current,  were  not  appropriate  to  the  facts  ;  it  has  been  my 
object  in  the  present  essay  to  show  that  certain  theories  on 
cell  life,  beautifully  constructed  and  ingeniously  defended  as 
they  have  been,  are  not  appropriate  to  the  facts.    I  am  far  from 
undervaluing  the  use  of  theory,  and  when   I   took  occasion 
before,  as  I  have  done  again  now,  to  emphasise  the  impor- 
tance of  attention  to  fact,  I   was  not  quite  so  ignorant  nor 
so  arrogant  as  Whitman  supposed.     The  motto  of  Goethe 


THE  PRESENT  POSITION  OF  CELL-THEORY.     241 

might  well  have  been  reversed  for  the  adornment  of  the 
title  pages  of  some  works  of  the  last  twenty  years.  "  Theory, 
reflection,  experience,"  the  last  named  to  be  fitted  in  as  best 
it  might. 

Since  the  above  passages  were  first  written  the  great 
work  of  Yves  Delage  has  came  into  my  hands.  Mine  is 
not  the  only  voice  crying  out  in  the  great  wilderness  of 
theories.  This  new  voice,  however,  is  far  greater  and 
more  powerful  than  mine.  The  reader  who  may  be  uncon- 
vinced by  my  clumsy  argumentation  should  turn  to  the 
pages  of  Delage.  For  clear  and  candid  exposition,  trenchant 
criticism,  and  rigorous  exposure  of  defects  of  reasoning, 
they  are  unsurpassed.  Now  that  this  part  of  my  work  is 
ended  I  feel  that  it  need  never  have  been  begun,  for  all 
that  I  have  had  to  say  has  been  said  in  greater  detail  and 
with  much  greater  force  by  Delage. 


FERNS,  APOSPOROUS  AND  APOGAMOUS. 

THE  normal  life  cycle  of  ferns,  owing  to  the  micro- 
scopic character  of  their  reproductive  apparatus, 
long  baffled  the  comprehension  of  botanists.  But  some 
half  a  century  ago,  starting  with  the  observations  of  Naegeli 
and  Suminski  and  culminating  in  those  of  Hofmeister, 
the  whole  course  of  their  ontogeny  has  been  cleared  up. 
The  fern  plant,  as  ordinarily  so-called,  produces  on  the 
back  of  its  leaves  or  fronds,  countless  numbers  of  spores, 
which  are  formed  within  minute  capsules  or  sporangia. 
When  these  spores  germinate  they  give  rise,  not  to  a  new 
fern  plant,  but  to  a  leaf-like  scale — the  Prothallus.  Upon 
the  lower  surface  of  this  the  sexual  organs  arise,  and  within 
them  the  sexual  cells  themselves  are  differentiated,  and  as  the 
result  of  the  fertilisation  of  one  of  the  female  cells  or 
oospheres,  by  the  male  cell  or  antherozoid,  a  new  fern  plant 
arises.  Thus  in  normal  cases  a  regular  alternation  of  a 
sexual  with  a  sexless  generation  is  seen.  But  although 
this  is  the  course  followed  by  the  vast  majority  of  the  ferns 
which  have  been  hitherto  investigated,  it  is  not  the  only 
one  open  to  the  plants.  Thus  Prof.  Farlow  in  1874  dis- 
covered that  the  formation  of  the  sporophore  (fern  plant) 
generation  might  arise  directly  from  the  oophore  (prothallus) 
generation,  without  the  intervention  of  sexual  organs,  by  a 
process  resembling  ordinary  budding.  De  Bary,  who 
followed  the  matter  further,  found  that  several  ferns  other 
than  that  examined  by  Farlow  reproduced  themselves  in 
the  same  fashion,  to  which  phenomenon  the  name  of 
Apogamy  was  given,  the  marriage  link  being  eliminated. 
Curiously  enough  De  Bary  found  that  a  variety  of  one  of 
our  most  vigorous  British  ferns  reproduced  itself  constantly 
in  this  asexual  manner,  though  the  common  form  exhibited 
no  abnormality  in  this  respect.  Recently,  however,  L. 
Kny,1  pursuing  these  investigations  further,   has  found  the 

1  Entivickehing  von   Aspidium   Filix   mas.   Sk'.,   i   Theil.,    L.   Kny, 
Berlin. 


FERNS,  APOSPOROUS  AND  APOGAMOUS.         243 

normal  form  to  reproduce  itself  in  both  ways,  and  since  his 
asexual  examples  occurred  in  thickly-sown  pots,  it  would 
appear  to  be  due  to  some  extent  to  a  starved  condition 
induced  by  overcrowding,  which  checks  the  formation  of 
the  archegonia,  and  leads  to  the  simple  budding  in  their 
place.  In  all  these  instances  the  young  plants  are  en- 
gendered upon  precisely  the  same  spots  on  the  prothallus 
as  the  sexual  one  would  occupy,  and  as  their  development 
and  appearance  are  identical,  it  is  only  by  preliminary 
watching  that  their  apogamic  origin  can  be  determined. 

A  case  of  Apogamy  (or  rather  two  cases),  however, 
recently  occurred  in  a  sowing  of  my  own,  which  is  quite 
distinct  from  any  I  have  seen  described.  A  sowing  of  a 
plumose  variety  of  Athyrium  jilix  foemina  failed  almost 
entirely,  only  two  or  three  prothalli  surviving.  One  of 
these  after  growing  very  large,  nearly  half  an  inch  across, 
remained  perfectly  dormant  the  whole  of  the  summer ; 
early  in  the  autumn,  however,  the  edge  of  the  prothallus 
began  to  grow  out  and  upwards  in  two  places,  and  eventu- 
ally two  slightly  curved  horns,1  each  about  one  quarter 
inch  long,  developed  perpendicularly,  one  on  each  side  of 
the  indentation  or  sinus  common  to  most  prothalli.  Later 
on,  at  a  short  distance  from  each  tip,  a  small  whitish  bulbil 
appeared  and  these  increased  in  size  until  the  circination  of 
several  fronds  was  plainly  visible,  a  small  crown  or  caudex 
being  developed.  No  roots,  however,  were  emitted,  and 
the  two  little  plants,  both,  be  it  remarked,  identically 
situated  and  very  like  in  form,  were  evidently  supported  by 
the  prothallic  root-hairs,  though  by  this  time  most  of  the 
prothallus  was  brown  and  dead.  Subsequently  I  placed  a 
piece  of  loam  in  contact,  and  into  this  both  plants  rooted 
and  fronds  were  sent  up,  the  first  of  which  had  no  less  than 
ten  pinnate  divisions  on  either  side.  It  was  thus,  it  will  be 
seen,  very  different  from  the  usually  simple  primary  fronds 
produced  either  sexually  or  apogamously  heretofore.  Later 
on  still,  noticing  that  the  tips  of  the  horns  were  showing 
signs  of  dilating,  I  cut  these  off  with  a  razor  and  laid  them 

1  Gard.  Chronicle,  10th  Nov.,  1894. 
17 


244  SCIENCE  PROGRESS. 

down,  two  apparently  normal  and  full-sized  prothalli  being 
the  present  result.  In  this  case  it  will  be  noted  that  both 
plants  were  far  removed  from  the  usual  site  of  reproduction, 
and  both  in  this  respect  and  in  their  vigorous  development 
are  differentiated  from  previously  cited  cases  of  apogamy. 
The  second  case  alluded  to  occurred  on  another  prothallus 
in  the  same  pan,  wherein  the  bulbil  developed  likewise 
upon  a  horn-like  excrescence,  but  on  the  centre  of  the  upper 
surface  of  the  prothallus.  This  bulbil  has  developed  into 
what  is  so  far  a  very  weakly  plant  of  a  different  type  to  the 
others,  but  otherwise  presenting  no  special  feature. 

Until  1884  the  Prothallus  had  always  been  regarded  as 
necessarily  the  offspring  of  the  spore,  but  in  the  autumn  of 
1883  a  presumed  barren  variety  of  Athyrium  jilix  fcemina 
{var.  C/arisstma)  was  sent  me  for  examination.  For 
twenty  years  this  plant  had  been  observed  to  produce  an 
immense  number  of  apparent  sori,  but  no  spores  were 
ripened  or  shed,  and  no  offspring  had  consequently  been 
raised.  Some  previous  observations  on  dorsal  bulbils,  i.e., 
bulbils  associated  with  the  spore  heaps  in  this  same 
species,  led  me  to  the  opinion  that  these  apparent  sori, 
which  consisted  of  green  pear-shaped  masses  instead  of  the 
capsules  proper  to  spores,  did  not  represent  bulbils,  but 
some  abnormality  in  the  development  of  the  sporangia. 
To  test  this  I  laid  down  portions  of  the  fronds,  and 
to  my  intense  surprise  these  pearshaped  bodies  com- 
menced at  once  to  grow  into  prothalli,  their  tips  dilating 
and  spreading,  while  root-hairs  and  subsequently  both 
archegonia  and  antheridia  appeared  in  abundance.  I  at 
once  gave  a  note  of  my  observations  at  the  Linnean 
Society  x  as  demonstrating  the  development  of  the  prothallus 
without  the  agency  of  the  spore.  The  following  season, 
pursuing  my  culture,  I  was  able  to  exhibit  a  number  of 
plants  and  such  material  as  satisfied  the  society  of  the 
facts  put  forward.2     Prof.    F.    O.    Bower 3   then   undertook 

1  "  Observations  on  a  Singular  Mode  of  Development  in  the  Lady  Fern 
{Athyrium  filix  fosmina)"  Linn.  Soc.  Journal  Botany,  vol  xxi.,  p.  354-7. 

2  "  Further  notes  on  ditto,''  ibid.,  vol.  xxi.,  pp.  358-60. 

3  "  On  Apospory  in  Ferns  (with  special  reference  to  Mr.  Charles  T. 
Druery's  observations),''  F.  O.  Bower,  ibid.,  vol.  xxi.,  pp.  360-68. 


FERNS,  APOSPOROUS  AND  APOGAMOUS.         245 

the  further  investigation  of  the  case,  and  found  that  the 
development  of  the  sorus  or  spore  heap  went  as  far  as  the 
formation  of  the  stalk  of  the  sporangium  or  spore  capsule, 
but  at  that  stage  it  stopped  and  a  vegetative  growth  set  in 
to  form  the  clusters  of  pear  or  club-shaped  bodies  which 
eventually  went  through  the  normal  evolution  of  prothalli 
and  sexual  plants.  Mr.  G.  B.  Wollaston  followed  by 
providing  material  from  a  variety  of  Polystichum  angulare 
in  his  possession,  wherein  the  elimination  of  the  spore  and 
the  entire  soral  apparatus  was  so  complete  that  the  prothalli 
were  developed  from  the  slender-pointed  tips  of  the  ultimate 
divisions  of  the  fern-frond.  Padley,  P.  ang.  var pule  her  rinmm 
was  the  plant  in  question,  and  as  it  chanced  that  several 
other  varieties  of  the  same  type  existed,  though  found  at 
widely  sundered  spots  in  England,  it  resulted  that  Dr. 
F.  W.  Stansfield  and  myself  found  the  same  character  in 
two  of  them.  Prof.  Bower  further  observed  that  soral 
apospory,  i.e.,  the  form  first  noted,  was  also  present  on 
Padley's  plants,  and  this  too  we,  Dr.  Stansfield  and  my- 
self, confirmed  in  the  others.  We  have  in  these  four 
examples,  and  in  the  genus  Polystichum  especially,  ample 
proof  that  the  spore  is  not  an  essential  preliminary  to 
the  existence  of  the  Prothallus,  but  that  the  latter  may 
be  developed  direct  from  the  tissues  of  the  Sporophore, 
precisely  as  this  latter  in  Apogamy  may  be  developed 
direct  from  those  of  the  oophore.1  Curiously  enough 
the  next  case  which  came  before  the  writer's  notice 
was  an  aposporous  seedling  of  the  same  variety  of  Lastrea 
(Aspidium)  determined  by  De  Bary  as  being  persistently 
apogamous,  viz.,  Lastrea  pseudo  ?nas  var.  cristata.  This 
case  was  distinct  from  previous  ones  as  it  was  a  young 
plant  and  not  an  adult,  which  produced  the  prothalli.  The 
tip  of  the  second  frond  evolved  from  the  prothallus  (the 
first  was  eaten  off  and  was  not  seen)  bore  a  prothallus  of 
the  normal  form.      Subsequently  this  and    the   succeeding 

1  Professor  F.  O.  Bower  subsequently  prepared  an  exhaustive  mono- 
graph "On  Apospory  and  Allied  Phenomena".  Linnean  Transactions, 
vol.  ii.,  part  14,  July,  1887,  to  which  reference  should  be  made  for  details 
of  the  preceding  cases. 


246  SCIENCE  PROGRESS. 

frond  became  covered  with  prothalli  developed  not  merely 
from  the  edges,  but  also  from  the  upper  surface,  and  being- 
pegged  down  produced  a  number  of  plants,  but  whether 
apogamously  or  not  I  cannot  say,  though  from  De  Bary's 
observations,  they  should  be  so.  It  is  worthy  of  remark 
that  in  some  of  these  youngsters,  the  line  between  the  two 
generations  of  sporophore  and  oophore  was  so  vague  that 
the  primary  fronds  were  simply  stalked  prothalli,  the  next 
frond  half  one  and  half  the  other,  while  the  fourth  or 
fifth  had  quite  outgrown  the  tendency  and  were  of  the 
typical  varietal  form.  This  plant  was  exhibited  and  de- 
scribed at  the  Linnean  Society,  3rd  November,  1892.1  Of 
the  next  two  cases  I  observed,  the  first  was  an  Athyrium 
found  in  Lancashire  and  exhibited  in  1893  at  the  meeting 
of  the  Pteridological  Society  at  Lancaster  by  Mr.  Bolton 
the  finder.  Immediately  on  seeing  it  I  remarked,  "How 
very  like  Col.  Jones's  Clarissima,"  simultaneously  with  which 
Mr.  Bolton  said,  "  It  is  strange,  but  it  never  ripens  its 
spores  "  ".  Turning  the  frond  over,  the  reason  was  clear, 
it  was  perfectly  white  with  aposporal  excrescences.  On 
submitting  these  to  culture  they  produce  plants  freely  by 
sexual  action,  but  of  two  types,  one  very  depauperate,  mere 
skeleton  plants,  and  the  other  of  the  parental  form  with 
occasional  reversion  towards  the  normal.  In  some  of  these 
young  plants  the  whitish  excrescences  are  plentiful  in 
fronds  only  an  inch  or  two  high,  and  there  are  evident 
signs  of  prothalloid  growth  at  the  tips  of  the  segments  as 
well,  pointing  to  apical  apospory  when  the  plants  are  more 
developed.  The  next  case  occurs  in  a  most  unlikely  species, 
especially  as  apical  apospory  is  in  question.  This  is  seen 
in  a  variety  of  Scolopendrium  vulgare  (S.  v.  cri spurn 
DrummondicB)  which  occurs  in  the  wild  state,  like  all  the  rest, 
characterised  by  being  frilled  and  crested,  and  having  more- 
over a  finely  fimbriated  edge  to  the  fronds.  Visiting  Mr. 
Bolton  to  inspect  the  Athyrium  last  cited,  I  saw  a  fine  plant  of 
this   fern,    and    it    immediately  struck  me  that  the   tips  of 

lu  Notes  on  an  Aposporous  Lastrea  (Nephrodium)"  Linn.  Soc.  Journal 
Botany,  vol.  xxix.,  pp.  479-82. 


FERNS,  APOSPOROUS  AND  APOGAMOUS.         247 

the  fimbriate  projections  were  remarkably  translucent.  I 
obtained  material,  laid  it  down,  and  at  once  prothalli  began 
to  develop  vigorously  from  every  point,  so  vigorously 
indeed  that  a  single  tip  has  formed  a  mass  of  prothalli  an 
inch  across  which  yielded  at  least  a  dozen  plants  of  the 
parental  form.1 

Dr.  F.  W.  Stansfield  has  recently  sent  me  prothalli 
developed  from  a  finely  fimbriated  form  of  Lastrea  of 
which  the  reputed  parent  is  that  already  described,  and  in- 
forms me  that  it  is  profusely  aposporous  though  fairly  de- 
veloped in  size. 

By  the  various  instances  of  this  phenomenon  so  far 
cited,  we  see  that  the  normal  life  cycles  of  the  ferns  in 
question  have  been  successively  shortened,  first  by  the 
elision  of  the  spore  and  then  by  that  of  the  whole  soral 
apparatus,  while  if  we  accept  De  Bary's  observations  as 
establishing  the  constant  apogamous  reproduction  of  L. 
pseudo  mas  cristata,  in  that  case,  it  is  shortened  almost  to 
the  utmost,  the  chain  being  simply  sporophore,  prothallus, 
sporophore.  Consistently  indeed  with  the  alternation  of 
generation  the  chain  could  not  apparently  be  shorter  since 
the  prothallus  being  eliminated  we  naturally  come,  or 
seem  to  come,  to  simple  bulbils,  such  as  occur  on  many 
ferns,  Aspleniuvi  bulbiferum  for  example.  In  the  final 
case,  however,  which  I  have  to  cite,  we  arrive  at  the 
elimination  even  of  the  prothallus  by  substitution  of  the 
frond  itself  as  the  oophore  or  egg-bearer,  the  archegonia 
and  antheridia  being  generated  upon  the  frond  without  the 
prior  formation  of  a  prothallus  proper.  In  a  small  plant 
of  Scolopendrium  vulgare  recently  sent  me  by  Mr.  E.  J. 
Lowe,  and  exhibited  by  me  at  the  Linnean  Society  in 
November  last,  although  a  definite  axis  of  growth  had  been 
formed  and  several  fronds  had  arisen  in  the  normal  spiral 
fashion  around  it,  indicating  that  the  prothallus  stage  had 
been  unmistakeably  passed,  each  of  these  fronds  bore  a 
thickened  cushion  at  its  tip  upon  which  were  seated  both 

1<lNote  on  Apospory  in  a  form  of  Scolopendrium  vulgare"  etc.,  Linn. 
Soc.  Journal,  vol.  xxx.,  pp.  281-84. 


248  SCIENCE  PROGRESS. 

antheridia  and  archegonia,  accompanied  by  aerial  roothairs, 
the  frond  itself  thus  assuming  the  functions  of  the  pro- 
thallus.  Mr.  Lowe  raised  a  number  of  similar  plants  on 
the  genesis  of  which  he  is  preparing  a  paper  which  I  will 
not  forestall ;  but  he  informs  me  that  in  time  they  throw 
off  this  aposporous  character.  Fronds  which  he  has  sent 
me,  and  which  I  have  laid  down,  have  developed  prothalli 
all  over  their  surface  and  at  all  terminals,  but  so  far  my 
cultures  are  too  recent  to  permit  me  to  report  the  advent  of 
plants. 

This  completes  the  sketch  of  the  cases  which  have 
come  under  my  immediate  notice,  but  considering  that,  in- 
cluding the  first  discovery,  the  phenomenon  has  been 
observed  in  no  less  than  nine  instances  in  our  limited  num- 
ber of  British  species,  viz.,  Lastrea  [Nephrodium)  two,  Athy- 
rium  filix  fcemina  two,  Polys  tic  hum  angular  e  three,  and 
Scolopendrium  vulgare  two ;  it  is  only  reasonable  to  ex- 
pect that  many  undiscovered  instances  must  occur  in  the 
innumerable  other  species  existent  throughout  the  world. 

Charles  T.  Druery. 


Science  progress* 


No.  28. 


June,   1896. 


Vol.  V. 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF 

HELIUM. 

THE  DISCOVERY  OF  THE  LINE  D3,   1868. 

IN  the  year  1868,  spectrum  analysis  was  first  utilised  in 
endeavouring"  to  unravel  the  message  which  was  con- 
veyed to  us  by  a  most  interesting  eclipse  observed  in  India. 
The  diagrams  will  indicate  the  kind  of  record  with  which 
we  have  to  deal  in  studying  these  celestial  hieroglyphics. 
We  are  in  one  part  dealing  with  the  long  waves  of  light, 
the  red  ;  we  are  in  the  other  dealing  with  the  shorter  waves 
of  light,  the  blue.  The  work  done  in  that  eclipse  is 
indicated  by  the  bright  lines — the  hieroglyphics — which, 
when  translated  as  they  have  been,  describe  for  us  the 
chemical  nature  of  the  particular  stuff  in  the  sun,  which 
made  him  put  on  a  blood-red  appearance  "  on  his  getting 
out  of  his  eclipse  ".  Taking  the  notes  in  the  light  scale 
which  are  lettered  in  the  ordinary  spectrum  of  sunlight,  in 
order  that  they  may  be  easily  recognised  and  remembered, 
we  learn  the  particular  qualities  of  the  light  emitted  by  the 
blood-red  streak. 

We  have  one  quality  represented  by  the  line  D,  another 
at  C,  and  another  at  F.  According  to  the  diagram,  one  of 
the  lines  is  in  the  position  of  D.  One  observer  said  it  was 
"at  D,  or  near  D  ". 

Soon  after  this  eclipse  was  observed  in  India,  a  method, 

18 


250 


SCIENCE  PROGRESS. 


long  before  formulated,  of  studying  the  blood-red  streak 
surrounding  the  sun  without  waiting  for  an  eclipse  was 
brought  into  operation. 

By  this  method  it  was  quite  easy  to  make  observations 
whenever  the  sun  was  shining,  perfectly  free  from  any  of 
the  difficulties  attending  the  hurry  and  the  worry  and  the 
excitement  of  an  eclipse,  which  lasts  only  a  few  seconds. 


B    C  -D  Ef  F  G 

Fig.  i. — Pogson's  diagram  of  the  spectra  of  the  sun's  surroundings  in  the 
Eclipse  of  1868.  The  bright  lines  seen  are  shown  in  the  upper  part 
of  the  diagram  ;  the  chief  lines  in  the  solar  spectrum,  red  to  the  left, 
blue  to  the  right,  are  shown  in  the  lower  part. 


A  1 

BC 

D             Eb 

F                    G 

H 

J 

.   1 

Ha 

H/»             Hr 

BB 

■ 

I 

Fig.  2. — Summation  of  the  observations  of  the  spectrum  of  the 
sun's  surroundings  in  the  Eclipse  of  1868.  (1)  Solar 
spectrum  showing  the  position  of  the  chief  lines.  (2) 
Rayet's  observations  of  bright  lines.  (3)  Herschel's  obser- 
vations of  bright  lines.     (4)  Tennant's. 

Further,  as  the  method  consists  of  throwing  an  image  of 
the  sun,  formed  by  a  telescope,  on  to  the  slit  of  a  spectro- 
scope, so  that  the  spectrum  of  the  sun's  edge  and  of  the 
sun's  surroundings  can  be  seen  at  the  same  time,  exact 
coincidence  or  want  of  coincidence  between  the  bright  and 
dark  lines  can  be  at  once  determined.      During  an  eclipse 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  251 

this  of  course  is  not  possible,  as  the  ordinary  spectrum  of 
the  sun,  with  its  tell-tale  dark  lines,  is  invisible  because  the 
sun,  as  we  ordinarily  see  it,  is  hidden  by  the  moon. 

Working,  then,  under  such  very  favourable  conditions,  it 
was  seen  that  there  was  certainly  a  red  line  given  by  this  lower 


1 

I 


Fig.  3. — The  exact  coincidence  of  the  red  line  with  the  dark  line  C. 

part  of  the  solar   atmosphere  coincident  with  the  very  im- 
portant line  in  the  solar  spectrum  which  we  call  C. 

Another  part  of  the  spectrum  in  the  blue-green  was 
examined,  and  there  again  it  was  seen  that  the  parts  out- 
side the  sun  gave  us  a  bright  line  exactly  in  the  position  of 


> ii    1 1  1  11  1 1  1 1  1 1  I  ■ 


Fig.  4. — The  exact  coincidence  of  the  blue-green  line  with  the  dark  line  F. 

the  obvious  dark  line  in  the  solar  spectrum  which  is  called 
F  ;  so  that  with  regard  to  those  two  most  important  lines, 
there  was  no  doubt  whatever  that  we  were  dealing  with 
the  substance  which  produces  these  dark  lines  in  the  solar 
spectrum. 


252 


SCIENCE  PROGRESS. 


Fig.  5  is  a  diagram  of  the  yellow,  or  rather  the  orange, 
part  of  the  solar  spectrum,  showing  two  very  important 
lines,  which  are  called  the  lines  D,  due  to  the  metal  sodium, 
the  investigation  of  which  was  just  as  important  in  solving 
the  celestial  hieroglyphics  we  call  spectral  lines  as  the 
Rosetta  stone  was  important  in  settling  the  question  of  the 
Egyptian  ones. 

Pogson,  in  referring  to  the  eclipse  of  1868,  said  that  the 
orange  line  was  "at   D,   or  near    D  ".     We   see  from  the 


D1  D2 


Fig.  5. — The  want  of  coincidence  of  the  orange  line  D3  with  the  dark 

lines  D1  and  D2. 

diagram  (Fig.  5)  that  the  new  method  indicated  that  "near 
D  "  was  the  true  definition.  The  line  in  this  position  in 
the  spectrum,  unlike  the  other  two  lines  which  I  have 
indicated,  has  no  connection  at  all  with  any  of  the  dark 
lines  in  the  ordinary  solar  spectrum.  We  were  therefore 
perfectly  justified  in  attaching  considerable  importance  to 
this  divergence  in  the  behaviour  of  this  line,  taking  the 
normal  behaviour  to  be  represented  by  the  two  strong  lines 
in  the  red  and  the  blue-green.  The  new  line  was  called 
D3  to  distinguish  it  from  the  sodium  lines  D1  and  D2. 

A  considerable  amount  of  work  was  done  with  regard 
to  the  orange  line.  It  was  found  that  there  was  no  sub- 
stance in  our  laboratories  which  could  produce  it  for  us, 
whereas  in  the  case  of  the  line  D  we  simply  had  to  burn 
some  sodium,  or  even  common  salt,  in  a  flame  to  produce 
it,  and  the  other  lines  in  the  red  and  the  blue-green  were 
easily  made  manifest  by  just  enclosing  hydrogen  in  a 
vacuum  tube,  and  passing  an  electric   current    through  it, 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  253 

or  observing  the  spectrum  of  a  spark  in  a  stream  of  coal- 
gas. 

Now  at  the  first  blush  it  looked  very  much  as  if  this 
line  was  really  due  to  the  same  element  which  produced 
the  others  at  C  and  F,  and  it  was  imagined  that  the  reason 
we  did  not  see  it  in  our  laboratories  was  because  it  was  a 
line  which  required  a  very  considerable  thickness  of  hydro- 
gen to  render  it  visible.  That  was  the  first  idea,  and  Dr. 
Frankland  and  myself  found  that  there  was  very  consider- 
able justification  for  this  view,  because  a  simple  calculation 
showed  that  the  thickness  of  the  solar  atmosphere,  which 
was  producing  that  orange  line  under  the  conditions  which 
enabled  us  to  see  it  in  our  instruments  by  looking  along  the 
edge  of  the  sun,  was  something  like  200,000  miles. 


ABC 
Fig.  6. — Changes  of  wave-length  of  the  F  hydrogen  line  when  a  solar 
cyclone  is  observed.  A,  the  change  towards  the  red  indicates  the 
retreating  side  of  cyclone.  C,  the  change  towards  the  blue  indicates 
the  advancing  side.  B,  the  whole  cyclone  is  included  in  the  width  of 
the  slit,  and  both  changes  of  wave-length  are  visible. 

Hence,  in  order  to  get  a  final  decision  on  this  point, 
there  was  nothing  for  it  but  to  tackle  the  question  from  a 
perfectly  different  point  of  view,  and  the  different  point  of 
view  was  this.  The  work  had  not  gone  on  very  long 
before  one  found  minute  alterations  in  the  positions  of  these 
lines  in  the  spectrum  ;  the  orange  line,  for  instance,  might 
sometimes  be  slightly  on  one  side,  and  sometimes  on  the 
other  of  its  normal  position.  Further  work  showed  that  in 
these  so-called  "  changes  of  wave-length  "  we  had  a  precious 
means  of  determining  the  rate  of  movement  of  the  gases 
and  vapours  in  the  solar  atmosphere. 

Fig.  6  indicates  how  these  changes  of  wave-lengths  are 


254  SCIENCE  PROGRESS. 

shown  in  the  spectroscope.  The  lines  are  contorted  in  both 
directions,  and  sometimes  to  a  very  considerable  extent, 
indicating  wind  movements  on  the  sun,  reaching  and  some- 
times exceeding  ioo  miles  a  second. 

We  had  here  a  means  of  determining  whether  the 
orange  line  was  produced  by  the  same  gases  which  gave  the 
red  and  blue  lines,  because  if  so,  when  we  got  any  altera- 
tion in  the  position  of  the  red  and  blue  lines,  which  always 
worked  together,  we  should  get  an  equivalent  alteration  in 
the  position  of  the  orange  one. 

I  found  that  the  orange  line  behaved  quite  differently 
from  either  the  red  or  the  blue  lines  ;  so  then  we  knew  that 
we  were  not  dealing  with  hydrogen  ;  hence  we  had  to  do 
with  an  element  which  we  could  not  get  in  our  laboratories, 
and  therefore  I  took  upon  myself  the  responsibility  of  coin- 
ing the  word  helium,  in  the  first  instance  for  laboratory 
use. 

This  kind  of  work  went  on  for  a  considerable  time,  and 
what  one  found  was,  that  very  often  in  solar  disturbances 
we  certainly  were  dealing  with  some  of  the  lines  of  sub- 
stances with  which  we  are  familiar  on  this  earth  ;  but  at  the 
same  time  it  was  very  remarkable  that  when  the  records 
came  to  be  examined,  as  they  ultimately  were  with  infinite 
care  and  skill,  it  was  found  that  not  only  did  we  get  this 
line  in  the  orange  indicating  an  unknown  element  associated 
with  substances  very  well  known,  like  magnesium,  but  that 
there  were  many  other  unknown  lines  as  well.  Within  a 
few  months  of  my  first  observations,  several  new  lines  about 
which  nothing  was  known  were  thus  observed. 

THE  DISCOVERY  OF   OTHER  UNKNOWN  LINES,  1869. 

The  place  of  the  orange  line  D3  I  determined  on 
20th  October,  1868.  Among  many  other  lines  behaving 
like  it,  two  at  wave-lengths  4923  and  5017  were  discovered 
in  June,  1869,  and  afterwards  another  at  6677,  while  Pro- 
fessor Young  noted  another  in  September,  1869,  at  4471. 
He  wrote  : — 

"  I  desire  to  call  special  attention  to  2581*5  [  =  4471  on 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  255 

Kirchhoff's  scale],  the  only  one  of  my  list,  by  the  way, 
which  is  not  given  on  Mr.  Lockyer's.  This  line,  which  was 
conspicuous  at  the  Eclipse  of  1869,  seems  to  be  always 
present  in  the  spectrum  of  the  chromosphere.  .  .  .  It  has  no 
corresponding  dark  line  in  the  ordinary  solar  spectrum,  and 
not  improbably  may  be  due  to  the  same  substance  that 
produces  D3." 

This  same  line  was  noted  also  by  Lorenzoni  and  named 
f.  Another  line  at  4026  was  added  later  by  Professor 
Young. 


Fig.  7. — Tacchini's  observations  of  two  slight  solar  disturbances 
showing  the  height  to  which  the  layers  of  the  different  gases 
extend.  Magnesium  vapour  is  highest  of  all,  and  is  furthest 
extended  ;  next  comes  a  gas  of  still  unknown  origin,  indicated 
by  a  line  at  1474  of  Kirchhoff's  scale  and  so  on. 

Then  with  regard  to  solar  disturbances.  Let  me  refer 
in  detail  to  a  diagram  indicating  some  results  arrived  at  by 
the  Italian  observers.  We  are  dealing  with  the  spectro- 
scopic record  of  two  slight  disturbances  in  a  particular  part 
of  the  sun's  atmosphere.  The  spectroscope  tells  us  that  in 
that  region  there  was  a  quantity  of  the  vapour  of  magnesium 
which  is  collected  in  that  place.  Then  we  find  that  another 
substance,  about  which  we  again  know  nothing  whatever, 
is  also  visible  in  that  region,  and  then  we  get  the  further 
fact  that  in  those  particular  disturbances  we  get  four  other 
spectral  lines  indicated  as  being  disturbed,  and  of  those  four 
lines  we  only  know  about  one. 


256  SCIENCE  PROGRESS. 

In  that  way  it  very  soon  became  perfectly  clear  to  those 
who  were  working  at  the  sun,  that  in  all  these  disturbances, 
or  at  all  events  in  most  of  them,  we  were  dealing  to  a  large 
extent  with  lines  not  seen  in  our  laboratories  when  dealing 
with  terrestrial  substances  ;  this  work  went  on  till  ultimately, 
thanks  to  the  labours  of  Professor  Young  in  America,  we 
had  a  considerable  list  of  lines  coming  from  known  and  un- 
known substances  which  had  been  observed  under  these 
conditions  in  solar  disturbances,  and  Professor  Young  was 
enabled  to  indicate  the  relative  number  of  times  these  lines 
were  visible.  For  instance,  the  lines  which  are  most 
frequently  seen  under  these  conditions  he  tabulated  as 
represented  by  the  number  100,  and  of  course  the  line 
which  was  least  frequently  seen  would  be  represented  by 
1  ;  and  therefore  from  these  so-called  "frequencies"  we 
got  a  good  idea  of  the  number  of  times  we  might  expect 
to  see  any  of  these  disturbance-lines  when  anything  was 
going  on  in  the  sun. 

It  was  this  kind  of  work  which  made  Tennyson  write 
those  very  beautiful  lines  : 

"  Science  reaches  forth  her  arms 
To  feel  from  world  to  world  ".1 

1  And  then  he  added  : 

"  and  charms 
Her  secret  from  the  latest  moon  ". 

I  mention  this  because  Tennyson,  whose  mind  was  saturated  with 
astronomy,  had  already  grasped  the  fact  that  what  had  already  been  done 
was  a  small  matter  compared  with  what  the  spectroscope  could  do ;  and 
now  the  prophecy  is  already  fulfilled,  for  by  means  of  the  spectroscopic 
examination  of  the  light  from  the  stars  we  can  tell  that  some  of  them  are 
double  stars,  that  is  to  say,  in  poetic  language,  stars  with  attendant  moons. 
Although  we  can  thus  charm  the  secret  from  each  moon  by  means  of  the 
spectroscope,  to  see  the  moon  it  would  require  (in  the  case  of  (3  Aurigse)  a 
telescope  not  eighty  feet  long,  but  with  an  object-glass  eighty  feet  in  dia- 
meter, because  the  closer  two  stars  are  together  the  greater  must  be  the 
diameter  of  the  object-glass,  independently  cf  its  focal-length  and  magnifying 
power. 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  257 

DR.   HILLEBRAND'S  RESEARCHES  ON   URANINITE,  1888. 

In  this  year  Dr.  Hillebrand,  one  of  the  officials  in  the 
Geological  Department  at  Washington,  was  engaged  upon 
the  chemical  examination  of  specimens  of  the  mineral 
uraninite  from  various  localities. 

He  dealt  with  crystals  which  he  put  in  a  vessel  contain- 
ing some  sulphuric  acid  and  water.  He  found  that  bubbles 
of  gas  were  produced  out  of  the  crystal  by  means  of  the 
sulphuric  acid.  He  collected  this  gas  and  came  to  the 
conclusion  that  it  was  nitrogen. 

This  result  was  new.      He  thus  wrote  about  it : — 

"In  consequence  of  a  certain  observation  "  [the  one  I 
have  just  referred  to]  "  and  its  results,  an  entirely  new 
direction  was  given  to  the  work,  and  its  scope  wonderfully 
broadened.  This  was  the  discovery  of  a  hitherto  un- 
suspected element  in  uraninite,  existing  in  a  form  of  com- 
bination not  before  observed  in  the  mineral  world." 

It  is  not  needful  here  to  follow  -Dr.  Hillebrand  through 
all  the  painstaking  and  patient  labour  he  cut  out  for  him- 
self to  explain  this  anomalous  behaviour.  Needless  to 
say  he  did  not  omit  to  employ  the  spectroscope  to  test  the 
nature  of  the  new  gas. 

His  observations  were  thus  described  : — 1 

"In  a  Geissler  tube  under  a  pressure  of  ten  milli- 
metres and  less,  the  gas  afforded  the  fluted  spectrum  of 
pure  nitrogen  as  brilliantly  and  as  completely  as  was  done 
by  a  purchased  nitrogen  tube.  In  order  that  no  possibility 
of  error  might  exist,  the  tube  was  then  reopened  and 
repeatedly  filled  with  hydrogen,  and  evacuated  till  only  the 
hydrogen  lines  were  visible.  When  now  filled  with  the 
gas  and  again  evacuated,  the  nitrogen  spectrum  appeared 
as  brilliantly  as  before,  with  the  three  bright  hydrogen  lines 
added." 

On  this  paragraph  I  may  remark  that  it  has  long  been 
known  that  gases  like  nitrogen  give  us  quite  distinct  spectra 
at  different    temperatures — one   fluted,   another   containing 

1<(On  the  Occurrence  of  Nitrogen  in  Uraninite,"  Bulletin,  No.  78, 
U.S.  Geol.  Survey,  1889-90,  p.  55. 


258  SCIENCE  PROGRESS. 

lines.  Which  of  these  we  shall  see  in  a  tube  will  depend 
upon  the  pressure  of  the  gas  and  the  electric  current  used. 
The  fluted  spectrum  of  nitrogen  is  very  bright  and  full  of 
beautiful  detail  in  the  orange  part  of  the  spectrum  ;  the  line 
spectrum,  on  the  other  hand,  is  almost  bare  in  that  region. 

It  is  important  to  note  that  it  so  happened 'that  the  pressure 
and  electric  conditions  employed  by  Dr.  Hillebrand  enabled 
him  generally  to  see  the  fluted  spectrum.  This  however 
was  not  always  the  case.  In  an  interesting  letter  to  Pro- 
fessor Ramsay  he  writes  (Proc.  Roy.  Soc,  vol.  lviii.,  p.  81): — 

"  Both  Dr.  Hallock  and  I  observed  numerous  bright 
lines  on  one  or  two  occasions,  some  of  which  apparently 
could  be  accounted  for  by  known  elements — as  mercury,  or 
sulphur  from  sulphuric  acid  ;  but  there  were  others  which  I 
could  not  identify  with  any  mapped  lines.  The  well-known 
variability  in  the  spectra  of  some  substances  under  varying 
conditions  of  current  and  degree  of  evacuation  of  the  tube 
led  me  to  ascribe  similar  causes  for  these  anomalous  appear- 
ances, and  to  reject  the  suggestion  made  by  one  of  us  in  a 
doubtfully  serious  spirit,  that  a  new  element  might  be  in 
question." 

Dr.  Hillebrand  concludes  his  paper  as  follows  : — 

"The  interest  in  the  matter  is  not  confined  merely  to  a 
solution  of  the  composition  of  this  one  mineral ;  it  is  broader 
than  that,  and  the  question  arises  :  May  not  nitrogen  be  a 
constituent  of  other  species  in  a  form  hitherto  unsuspected 
and  unrecognisable  by  our  ordinary  chemical  manipulations? 
And,  if  so,  other  problems  are  suggested  which  it  is  not  now 
in  order  to  discuss." 

D3  AND  OTHER  UNKNOWN  LINES  IN  NEBULA,   1890. 

A  negative  of  the  nebula  of  Orion,  taken  at  my  observatory 
at  Westgate-on-Sea  in  1890,  contains  fifty-six  lines,  and  of 
course  by  determining,  as  we  have  been  able  to  do  approxi- 
mately, the  wave-lengths — the  positions  of  these  lines  in 
the  spectrum — we  can  determine  the  exact  light  notes 
represented,  and  therefore  the  substances  which  produce 
them.      In  this  spectrum  of  the  nebula  of  the   Orion  were 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  259 

lines  of  unknown  origin  exactly  coinciding  with  those  un- 
known lines  which  I  have  already  referred  to  as  having 
been  seen  in  the  sun's  atmosphere.  Some  of  the  un- 
known lines  in  that  atmosphere,  those  that  we  have  not 
been  able  to  see  in  our  laboratories,  are  identical  in  position 
with  some  of  the  unknown  lines  in  the  nebula  of  Orion. 

I  may  remark  that  as  early  as  1886  Dr.  Copeland  had 
discovered  D3  in  the  visible  spectrum  of  the  nebula,  and 
in  a  letter  to  him  I  had  suggested  that  another  line  he  had 
recorded  at  447  might  be  Lorenzoni's  f\  this  he  thought 
to  be  probable.  The  matter  was  set  for  ever  at  rest  by 
the  photograph  which  established  the  presence  of  4471  and 
4026  as  well,  already  noted  as  a  solar  line. 

Professor  Campbell,  of  the  Lick  Observatory,  obtained 
other  photographs  of  the  spectrum  of  the  nebula  some  two 
or  three  years  after  mine  was  taken.  In  the  following  list 
of  lines  in  my  photograph  an  asterisk  denotes  that  Campbell 
gives  a  line  nearly  in  the  same  position.  He  recorded 
no  line  which  did  not  appear  on  my  photograph. 

3896* 
3888* 
401 1 
4026* 
4121* 

4143* 

4168 

4390* 

4472* 

4716* 

4924 


5875-8  =  D3 
THE  SAME  UNKNOWN   LINES  OCCUR  IN  THE  STARS,   1892. 

About  the  year  1890  I  began  the  photography  of  stellar 
spectra  at  Kensington,  with  special  reference  to  their 
classification  on  the  basis  of  the  chemical  constituents 
established  by  their  spectra.  By  1892  several  important 
results  had  been  obtained,  while  the  progress  of  this  branch 
of  science  lately  has  been  so  considerable  that  any  state- 
ment  regarding  the   positions   of  lines,  and  therefore   the 


260  SCIENCE  PROGRESS. 

chemical  origins  of  them,  may  be  made  with  a  considerable 
amount  of  certainty  as  depending  upon  very  accurate  work. 

The  various  classes  in  which  the  stars  have  been 
classified  by  different  observers  according  to  their  spectra 
are  discussed  elsewhere,  but  some  of  the  more  salient  differ- 
ences must  be  pointed  out  here  ;  thus  we  have  stars  with 
many  lines  in  their  spectra,  others  with  comparatively  few. 
I  will  take  the  many-lined  stars  first. 

The  diagram  (Fig.  8)  represents  the  spectrum  of 
Arcturus,  a  star  the  spectrum  of  which  closely  resembles 
that  of  the  sun.  In  a  Cygni  we  have  another  star  with 
many  lines,  but  here  we  note,  when  we  leave  the  hydrogen 
on  one  side  and  deal  with  the  other  stronger  lines,  that 
there  is  little  relation  between  the  solar  spectrum  and  these 
lines. 

I  next  come  to  the  stars  with  few  lines  :  these  are  well 
represented  by  many  of  the  chief  stars  in  the  Constellation 
of  Orion.      Bellatrix  is  given  as  an  example  (Fig.  9). 

Then,  I  have  next  to  say  that  in  the  photographs  of  the 
spectra  of  many  stars,  chiefly  of  those  more  or  less  like 
Bellatrix,  we  found  the  same  lines  which  we  have  so  far 
classified  as  unknown  for  the  reason  that  in  our  laboratories 
we  have  not  been  able  to  get  any  lines  which  correspond 
with  them.  I  again  mention  D3,  4471  and  4026,  previously 
noted  as  appearing  both  in  the  chromosphere  and  in  the 
nebula  of  Orion. 

But  the  thing  is  much  more  interesting  even  than  this  ; 
not  only  these,  but  all  the  chief  unknown  lines  appearing  in 
the  nebula  of  Orion  are  also  found  in  these  stars.  And  this 
is  so  absolutely  true  that  there  is  no  necessity  to  give  a  list 
of  the  unknown  lines  seen  in  Bellatrix  ;  every  one  of  them 
given  in  the  nebula  has  found  its  place,  and  (so  far)  practically 
no  others. 

This  of  course  marked  a  great  development  of  the 
inquiry,  and  makes  the  question  of  the  unknown  lines 
more  important  than  ever. 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  261 


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262  SCIENCE  PROGRESS. 

PHOTOGRAPHIC  RESULTS  DURING  A  SOLAR  ECLIPSE,  1893. 

A  method  which  was  first  employed  by  Respighi  and 
myself  during  the  eclipse  of  1871,  was  employed  on  a 
large  scale  and  with  great  effect  during  the  eclipse  of  1893. 
The  light  proceeding  from  the  luminous  ring  round  the 
dark  moon  was  made  to  give  us  a  series  of  rings,  represent- 
ing each  bright  line  seen  by  the  ordinary  method  on  a 
photographic  plate.  The  observers  this  time  were  stationed 
in  West  Africa  and  in  Brazil.  The  African  station  was 
up  one  of  the  rivers,  not  very  far  away  from  the  town  of 
Bathurst.  The  Brazilian  station  was  near  Para  Curu.  The 
same  instrument  which  was  previously  referred  to  as  used  for 
obtaining  photographs  of  the  stars  was  sent  to  the  African 
station  in  order  that  photographs  of  the  eclipse  of  the  sun 
might  be  taken  on  exactly  the  same  scale  as  the  photo- 
graphs of  the  stars  had  been,  so  that  the  stellar  and  solar 
records  in  the  photographs  might  be  compared.  The  results 
obtained  by  Messrs.  Fowler  and  Shackleton,  who  were  in 
charge  of  the  instruments  at  the  two  stations,  will  be  gathered 
from  the  accompanying  diagrams,  Figs.  10  and  11. 

We  get  more  or  less  complete  rings  when  we  are  deal- 
ing with  an  extended  arc  of  the  chromosphere,  or  lines  of 
dots  when  any  small  part  of  it  is  being  subjected  to  a  dis- 
turbance which  increases  the  temperature  and,  possibly, 
the  numbers  of  the  different  vapours  present. 

The  efficiency  of  this  method  of  work  with  the  dis- 
persion employed  turns  out  to  be  simply  marvellous,  and  in 
securing  such  valuable  and  permanent  records  as  these,  we 
have  done  very  much  better  than  if  we  had  contented  our- 
selves with  the  style  of  observations  that  I  have  referred  to 
as  having  been  made  in  1871. 

As  was  expected  the  comparison  between  solar  and 
stellar  records  thus  rendered  possible  enabled  a  very  great 
advance  to  be  made. 

On  examining  these  eclipse  records,  we  find  that  we 
have  to  do  exactly  with  those  unknown  lines  which  had 
already  been  photographed  in  the  stars  and  in  the  nebulas. 

As  was  to  be  expected  we,  of  course,  deal  with  the  lines 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  263 


264  SCIENCE  PROGRESS. 

recorded  in  the  first  observations  of  the  solar  disturbances, 
and  chronicled  in  that  table  of  Professor  Young's  to  which 
I  have  already  called  attention  ;  but  the  important  thing  is 
the  marvellously  close  connection  between  eclipse-  and  star- 
spectrum  photographs  so  far  as  the  "unknown  lines"  are 
concerned. 

Nearly  all  the  lines  given  in  the  table  on  p.  259  as 
visible  in  the  Nebula  of  Orion  and  afterwards  found  in 
Bellatrix,  are  also  among  the  lines  photographed  during  the 
eclipse. 

DISCOVERY  OF  A  TERRESTRIAL  SOURCE  OF  HELIUM,  1895. 

The  year  1894  was  made  memorable  by  the  announce- 
ment of  the  discovery  by  Lord  Rayleigh  and  Professor 
Ramsay  of  a  new  gas  called  argon,  and  you  know  that  the 
discovery  was  brought  about  chiefly  in  the  first  instance 
by  the  very  accurate  observations  of  Lord  Rayleigh,  who 
found  that  when  he  was  determining  the  weight  of  air  in 
the  globe  of  a  certain  capacity,  the  weight  depended  upon 
the  source  from  which  he  got  the  nitrogen. 

From  the  nitrogen  from  atmospheric  air  he  obtained  one 
weight,  and  from  that  obtained  by  certain  chemical  pro- 
cesses he  obtained  another,  and  ultimately  it  was  found  that 
there  was  an  unknown  element  which  produced  these  results, 
these  various  changes  in  the  weight,  and  as  a  consequence 
we  had  the  1895  discovery  of  argon. 

Early  in  1895  it  struck  Mr.  Miers,  of  the  British 
Museum,  that  it  might  be  desirable  to  draw  attention  to 
the  nitrogen  which  we  have  seen  Dr.  Hillebrand  in  1888 
obtaining  from  his  crystal  of  uraninite  ;  his  observations,  of 
course,  were  more  in  the  mind  of  Mr.  Miers  than  in  the 
minds  of  the  pure  chemists.  He  therefore  communicated 
with  Professor  Ramsay,  who  lost  no  time,  because  it  was 
very  interesting  to  study  every  possible  source  of  nitrogen 
and  see  what  its  behaviour  was  in  regard  to  the  quantity 
of  argon  that  it  produced,  and  in  the  relation  generally  of  the 
gas  to  the  argon  which  was  produced  from  it. 

Professor  Ramsay  treated  uraninite  in  exactly  the  same 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  265 


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266  SCIENCE  PROGRESS. 

way  that  Dr.  Hillebrand  had  done  in  1888.  The  gas 
obtained  as  Dr.  Hillebrand  had  obtained  it  was  eventually- 
submitted  to  a  spectroscopic  test,  following  Dr.  Hillebrand's 
example.      But  here  a  noteworthy  thing  comes  in. 

It  so  happened  that  the  pressure  and  electrical  conditions 
employed  by  Professor  Ramsay  were  so  different  from  those 
used  by  Dr.  Hillebrand  that,  although  nitrogen  was  un- 
doubtedly present,  the  fluted  spectrum  which,  as  I  have 
previously  stated,  floods  the  orange  part  of  the  spectrum 
with  luminous  details,  was  absent.  But  still  there  was 
something  there. 

Judge  of  Professor  Ramsay's  surprise  when  he  found 
that  he  got  a  bright  orange  line  ;  that  was  the  chief  thing, 
and  not  the  strong  suggestion  of  the  spectrum  of  nitrogen. 
Careful  measurements  indicated  that  the  twenty-six-year- 
old  helium  had  at  last  been  run  to  earth,  D3  was  at  last 
visible  in  a  laboratory.  Professor  Ramsay  was  good  enough 
to  send  specimens  of  the  tubes  containing  this  gas  round 
to  other  people,  and  he  sent  one  of  them  to  me. 

I  received  Professor  Ramsay's  tube  on  28th  March,  but 
it  was  not  suitable  for  the  experiments  I  wished  to  make. 

On  29th  March,  therefore,  as  Professor  Ramsay  was 
absent  from  England,  in  order  not  to  lose  time  I  determined 
to  see  whether  the  gas  which  had  been  obtained  by  chemical 
processes  would  not  come  over  by  heating  in  vacuo,  after  the 
manner  described  by  me  to  the  Royal  Society  in  1879/and  Mr. 
L.  Fletcher  was  kind  enough  to  give  me  some  particles  of 
uraninite  (broggerite)  to  enable  me  to  make  the  experiment. 

This  I  did  on  30th  March,  and  it  succeeded  ;  the  gas 
giving  the  yellow  line  came  over,  associated  with  hydrogen, 
in  good  quantity. 

From  30th  March  onwards  my  assistants  and  myself 
had  a  very  exciting  time.  One  by  one  the  unknown  lines 
I  had  observed  in  the  sun  in  1868  were  found  to  belong  to 
the  gas  I  was  distilling  from  broggerite ;  not  only  D3  but 
4923,  5017,  4471  (Lorenzoni's/),  6677  (the  B  C  of  Fig.  7), 
referred  to  previously,  and  many  other  solar  lines,  were  all 
caught  in  a  few  weeks. 

1  Roy.  Soc.  Proc,  vol.  xxix.,  p.  266. 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  267 

But  this  was  by  no  means  all.  The  solar  observations 
had  been  made  by  eye,  and  referred  therefore  to  the  less 
refrangible  part  of  the  spectrum,  but  I  had  obtained  and 
studied  hundreds  of  stellar  photographs,  so  I  at  once  pro- 
ceeded to  photograph  the  gas  and  compare  its  more  re- 
frangible lines  with  stellar  lines. 

Here,  if  possible,  the  result  was  still  more  marvellous. 
In  the  few-lined  stars  by  6th  May  I  had  caught  nearly  all 
the  most  important  lines  at  the  first  casts  of  the  spectroscopic 
net.  Fig.  1 5,  which  includes  some  later  results,  will  give  an 
idea  of  the  tremendous  revelation  which  had  been  made  as 
to  the  chemistry  of  some  of  the  stages  of  star-life.  I 
pointed  out  on  8th  May  that  we  had  already  "run  home  " 
the  most  important  lines  in  the  spectra  of  Group  III.  in 
which  stars  alone  we  find  D3  reversed. 

These  results  enabled  us  at  once  to  understand  how  it 
was  that  the  "unknown  lines"  had  been  seen  both  in  the 
sun's  chromosphere  and  some  nebulae  and  stars.  The  gas 
obtained  from  the  minerals  made  its  appearance  in  the 
various  heavenly  bodies  in  which  the  conditions  of  the 
highest  temperatures  were  present ;  and  the  more  the  work 
goes  on,  we  find  that  this  gas  is  really  the  origin  of  most, 
but  certainly  not  of  all,  of  the  unknown  lines  which  have 
been  teasing  astronomical  workers  for  the  last  quarter  of  a 
century. 

THE  FIRST  INVESTIGATIONS  OF  THE  SPECTRUM  OF  THE 

GAS  FROM  CLEVEITE. 

The  dates  of  the  papers  communicated  to  the  Royal 
Society  recording  the  observations  of  the  lines  in  the  gas 
obtained  from  minerals  which  had  been  previously  recorded 
are  as  follows  : — 


4026 


4922 

The  lines  at  667   and   5016  had  been  previously  seen 
by  Thalen  (Comptes  Rendus,  16th  April,  1895). 


25  th  April,    - 

-     447i 

4144 

8th  May, 

-     667 

4388 

9th  May, 

-     3889 

28th  May,     - 

-     7065 

29th  May,     - 

-     5048 

5016 

268  SCIENCE  PROGRESS. 

Although  the  general  distribution  and  intensities  of  the 
lines  in  the  gases  from  broggerite  and  cleveite  sufficiently 
corresponded  with  some  of  the  chief  "  unknown  lines  "  in 
the  solar  chromosphere  and  some  of  the  stars  to  render 
identity  probable,  it  was  necessary  to  see  how  far  the  con- 
clusion was  sustained  by  detailed  investigations  of  the 
wave-lengths  of  the  various  lines. 

EMPLOYMENT  OF  HIGH  DISPERSION. 

This  was  practically  a  separate  branch  of  the  work,  as 
the  observations  had  to  be  made  in  the  observatory.  Next 
I  give  here  the  observations  relating-  to  D3,  4471. 

The  Orange  Line,  A  5875*9. — Immediately  on  receiving 
from  Professor  Ramsay,  on  28th  March,  a  small  bulb  of  the 
gas  obtained  from  cleveite,  a  provisional  determination  of 
wave-length  was  made  by  Mr.  Fowler  and  myself,  in  the 
absence  of  the  sun,  by  micrometric  comparisons  with  the  D 
lines  of  sodium,  the  resulting  wave-length  being  5876*07 
on  Rowland's  scale.  It  was  at  once  apparent,  therefore, 
that  the  gas  line  was  not  far  removed  from  the  chromo- 
spheric  D3,  the  wave-length  of  which  is  given  by  Rowland 

as  5875'98. 

The  bulb  being  too  much  blackened  by  sparking  to  give 
sufficient  luminosity  for  further  measurements,  I  set  about 
preparing  some  of  the  gas  for  myself  by  heating  broggerite 
in  vacuo,  in  the  manner  I  have  already  described.  A  new 
measurement  was  thus  secured  on  30th  March,  with  a 
spectroscope  having  a  dense  Jena  glass  prism  of  6o°  ;  this 
gave  the  wave-length  5876*0. 

On  5th  April,  I  attempted  to  make  a  direct  comparison 
with  the  chromospheric  line,  but  though  the  lines  were 
shown  to  be  excessively  near  to  each  other,  the  observa- 
tions were  not  regarded  as  final. 

Professor  Ramsay  having  been  kind  enough  to  furnish 
me,  on  1st  May,  with  a  vacuum  tube  which  showed  the 
orange  line  very  brilliantly,  a  further  comparison  with  the 
chromosphere  was  made  on  4th  May.  The  observations 
were  made  by  Mr.  Fowler,  in  the  third  order  spectrum  of 
a  grating  having  14,438  lines  to  the  inch,  and  the  observing 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  269 

telescope  was  fitted  with  a  high  power  micrometer  eye- 
piece ;  the  dispersion  was  sufficient  to  easily  show  the 
difference  of  position  of  the  D3  line  on  the  east  and  west 
limbs,  due  to  the  sun's  rotation.  Observations  of  the 
chromosphere  were  therefore  confined  to  the  poles. 

During  the  short  time  that  the  tube  retained  its  great 
brilliancy,  a  faint  line,  a  little  less  refrangible  than  the 
bright  orange  one,  and  making  a  close  double  with  it,  was 
readily  seen  ;  but  afterwards  a  sudden  change  took  place, 
and  the  lines  almost  faded  away.  While  the  gas  line  was 
brilliant,  it  was  found  to  be  "  the  least  trace  more  refrangible 
than  D3,  about  the  thickness  of  the  line  itself,  which  was 
but  narrow"  ("Observatory  Note  Book").  The  sudden 
diminution  in  the  brightness  of  the  lines  made  subsequent 
observations  less  certain,  but  the  instrumental  conditions 
being  slightly  varied,  it  was  thought  that  the  gas  line  was 
probably  less  refrangible  than  the  D3  line  by  about  the 
same  amount  that  the  first  observation  showed  it  to  be 
more  refrangible.  Giving  the  observations  equal  weight, 
the  gas  line  would  thus  appear  to  be  probably  coincident 
with  the  middle  of  the  chromospheric  line,  but  if  extra 
weight  be  given  to  the  first  observation,  made  under  much 
more  favourable  conditions,  the  gas  line  would  be  slightly 
more  refrangible  than  the  middle  of  the  chromosphere  line. 

Pressure  of  other  work  did  not  permit  the  continuation 
of  the  comparisons.  In  the  meantime,  Runge  and  Paschen 
announced  (Nature,  vol.  Hi.,  p.  128)  that  they  also  had  seen 
the  orange  line  of  the  cleveite  gas  to  be  a  close  double, 
neither  component  having  exactly  the  same  wave-length  as 
D3,  according  to  Rowland. 

They  give  the  wave-length  of  the  brightest  component  as 
5878*883,  and  the  distance  apart  of  the  lines  as  0*323. 

This  independent  confirmation  of  the  duplicity  of  the 
gas  line  led  me  to  carefully  re-observe  the  D3  line  in  the 
chromosphere  for  evidences  of  doubling.  On  14th  June 
observations  were  made  by  Mr.  Shackleton  and  myself  of 
the  D3  line  in  the  third  and  fourth  order  spectra  under 
favourable  conditions ;  "  the  line  was  seen  best  in  the  fourth 
order,  on  an  extension  of  the  chromosphere  or  prominence 


270  SCIENCE  PROGRESS. 

on  the  north-east  limb  of  the  sun.  The  D3  line  was  seen 
very  well,  having  every  appearance  of  being  double,  with  a 
faint  component  on  the  red  side,  dimming  away  gradually  ; 
the  line  of  demarcation  between  the  components  was  not 
well  marked,  but  it  was  seen  better  in  the  prominence  than 
anywhere  else  on  the  limb  "  ("  Observatory  Note  Book  "). 

It  became  clear,  then,  that  the  middle  of  the  chromo- 
sphere line,  as  ordinarily  seen,  and  as  taken  in  the 
comparison  of  4th  May,  does  not  represent  the  place  of 
the  brightest  component  of  the  double  line,  so  that  exact 
coincidence  was  not  to  be  expected. 

The  circumstance  that  the  line  is  double  in  both  gas 
and  chromosphere  spectrum,  in  each  the  less  refrangible 
component  being  the  fainter,  taken  in  conjunction  with  the 
direct  comparisons  which  have  been  made,  rendered  it 
highly  probable  that  one  of  the  gases  obtained  from  cleveite 
is  identical  with  that  which  produces  the  D3  line  in  the 
spectrum  of  the  chromosphere. 

Other  observers  have  since  succeeded  in  resolving  the 
chromospheric  line.  On  20th  June,  Professor  Hale  found 
the  line  to  be  clearly  double  in  the  spectrum  of  a  promin- 
ence, the  less  refrangible  component  being  the  fainter,  and 
the  distance  apart  of  the  lines  being  measured  as  0*357 
tenth -metres  (Ast.  JVac/i.,  3302). 

The  doubling  was  noted  with  much  less  distinctness  in 
the  spectrum  of  the  chromosphere  itself  on  24th  June. 
Professor  Hale  points  out  that  Rowland's  value  of  the  wave- 
length (as  well  as  that  of  5875*924,  determined  by  himself 
on  19th  and  20th  June)  does  not  take  account  of  the  fact 
that  the  line  is  a  close  double. 

Dr.  Huggins,  after  some  failures,  observed  the  D3  line 
to  be  double  on  10th  July  [Ast.  Nack.,  3302);  he  also 
notes  that  the  less  refrangible  component  was  the  fainter, 
and  that  the  distance  apart  of  the  lines  was  about  the  same 
as  that  of  the  lines  in  the  gas  from  cleveite,  according  to 
Runge  and  Paschen. 

It  may  be  added,  that  in  addition  to  appearing  in  the 
chromosphere,  the  D3  line  has  been  observed  as  a  bright 
line   in   nebulae    by   Dr.    Copeland,    Professor   Keeler  and 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  271 

others  ;  in  /3  Lyrae  and  other  bright  line  stars  ;  and  as  a 
dark  line  in  such  stars  as  Bellatrix,  by  Mr.  Fowler,  Pro- 
fessor Campbell  and  Professor  Keeler.  In  all  these  cases 
it  is  associated  with  other  lines,  which,  as  I  shall  show  pre- 
sently, are  associated  with  it  in  the  spectra  of  the  new  gases. 

The  Blue  Line,  A  4471*8. — A  provisional  determination 
on  2nd  April  of  the  wave-length  of  a  bright  blue  line,  seen 
in  the  spectrum  of  the  gases  obtained  from  a  specimen  of 
cleveite,  showed  that  it  approximated  very  closely  to  a 
chromospheric  line,  the  frequency  of  which  is  stated  as  100 
by  Young. 

This  line  was  also  seen  very  brilliantly  in  the  tube 
supplied  to  me  by  Professor  Ramsay  on  1st  May,  and  on 
6th  May  it  was  compared  directly  with  the  chromosphere 
line  by  Mr.  Fowler.  The  second  order  grating  spectrum 
was  employed.  The  observations  in  this  region  were  not 
so  easy  as  in  the  case  of  D3,  but  with  the  dispersion  em- 
ployed, the  gas  line  was  found  to  be  coincident  with  the 
chromospheric  one.  In  this  case  also,  the  chromosphere 
was  observed  at  the  sun's  poles,  in  order  to  eliminate  the 
effects  due  to  the  sun's  rotation. 

Besides  appearing  in  the  spectrum  of  the  chromosphere, 
the  line  in  question  is  one  of  the  first  importance  in  the 
spectra  of  nebulae,  bright  line  stars,  and  of  the  white  stars 
such  as  Bellatrix  and  Rigel. 

The  Infra-red  Line,  \  7065*5. — In  addition  to  D3  and 
the  line  at  447 1  '8,  there  is  a  chromospheric  line  in  the  infra- 
red which  also  has  a  frequency  of  100,  according  to  Young. 
On  28th  May  I  communicated  a  note  to  the  Royal  Society 
stating  that  this  line  had  been  observed  in  the  spectrum  of 
the  gases  obtained  from  broggerite  and  euxenite  {Roy.  Soc. 
Proc,  vol.  lviii.,  p.  192),  solar  comparisons  having  con- 
vinced me  that  the  wave-length  of  the  gas  line  corresponded 
with  that  given  by  Young  ;  and  I  added  :  "  It  follows,  there- 
fore, that  besides  the  hydrogen  lines  all  three  chromospheric 
lines  in  Young's  list  which  have  a  frequency  of  100  have 
now  been  recorded  in  the  spectra  of  the  new  gas  or  gases 
obtained  from  minerals  by  the  distillation  method  ". 

M.    Deslandres,    of    the    Paris   Observatory,    has   also 


272  SCIENCE  PROGRESS. 

observed  the  line  at   7065    in  the  gas  obtained  from  the 
cleveite  (Comptes  Rendus,  17th  June,  1895,  p.  1 331). 

A  great  deal  of  work  has  been  done  upon  these  gases 
from  other  points  of  view  than  those  which  affect  their 
cosmical  relations,  and  perhaps  I  may  be  allowed  next  to 
refer  to  some  of  the  results  which  have  been  obtained  by 
myself. 

HELIUM   NOT   CONNECTED   WITH   ARGON. 

The  first  point  is  that  the  gas  from  the  minerals  contains 
no  argon.  Dr.  Ramsay  in  his  first  experiments  came  to  the 
conclusion  that  the  spectra  of  argon  and  helium  contained 
many  common  lines ;  indeed  at  first  the  observed  coin- 
cidences were  so  remarkable  that  he  came  to  the  conclusion 
that  the  connection  was  so  close  that  atmospheric  argon  con- 
tained a  gas  absent  from  the  argon  seen  in  his  helium  tube. 

This  statement  was  subsequently  withdrawn,  but  the 
compound  nature  both  of  argon  and  helium  was  suggested 
by  the  fact  that  there  were  lines  common  to  the  two  gases. 
These  lines  were  in  the  red  ;  one  coincidence  I  found  broke 
down  with  moderate  dispersion,  the  other  yielded  subse- 
quently to  the  still  greater  dispersion  employed  by  Drs. 
Runge  and  Paschen.  It  may  be  also  stated  here  that  I  have 
not  found  a  single  coincidence  between  argon  and  any  line 
in  the  spectrum  of  any  celestial  body  whatever.  This 
happens,  as  everybody  knows,  also  in  the  case  of  oxygen, 
nitrogen,  chlorine,  and  the  like. 

THE   CLEVEITE   GAS  A   COMPOUND. 

The  first  spectroscopic  observations  made  it  perfectly 
obvious  that  the  gas  as  obtained  from  uraninite  is  a  mixture 
of  gases,  that  the  gas  which  gives  the  yellow  line  is  not  an 
isolated  one,  but  is  mixed  up  with  other  gases  which  give 
other  lines. 

In  May  I  wrote  as  follows  : — 1 

"  The  preliminary  reconnaissance  suggests  that  the  gas 
obtained  from  broggerite  by  my  method  is  one  of  complex 
origin. 

1  Proc.  R.  S.,  Iviii.,  p.  114. 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  273 

"  I  now  proceed  to  show  that  the  same  conclusion  holds 
good  for  the  gases  obtained  by  Professors  Ramsay  and 
Cleve  from  cleveite. 

"  For  this  purpose,  as  the  final  measures  of  the  lines  of 
the  gas  as  obtained  from  cleveite  by  Professors  Ramsay  and 
Cleve  have  not  yet  been  published,  I  take  those  given  by 
Crookes  and  Cleve,  as  observed  by  Thalen. 

"  The  most  definite  and  striking  result  so  far  obtained  is 
that  in  the  spectra  of  the  minerals  giving  the  yellow  line 
I  have  so  far  examined,  I  have  never  once  seen  the  lines 
recorded  by  Crookes  and  Thalen  in  the  blue.  This  demon- 
strates that  the  gas  obtained  from  certain  specimens  of 
cleveite  by  chemical  methods  is  vastly  different  from  that 
obtained  by  my  method  from  certain  specimens  of  brog- 
gerite,  and  since,  from  the  point  of  view  of  the  blue  lines, 
the  spectrum  of  the  gas  obtained  from  cleveite  is  more 
complex  than  that  of  broggerite,  the  gas  itself  cannot  be 
more  simple. 

"  Even  the  blue  lines  themselves,  instead  of  appearing 
en  bloc,  vary  enormously  in  the  sun,  the  appearances  being 

4922  (4921-3)  =  thirty  times 
4713  (47 1 2-5)  =  twice. 

"  These  are  not  the  only  facts  which  can  be  adduced  to 
suggest  that  the  gas  from  cleveite  is  as  complex  as  that 
from  broggerite." 

It  is  seen  that  quite  early  in  the  inquiry  we  had  not  only 
spectroscopic  evidence  in  the  laboratory  which  was  com- 
plete in  itself,  but  that  the  case  was  greatly  strengthened 
when  the  behaviour  of  the  various  lines  in  the  sun  and  stars 
was  also  brought  into  evidence. 

In  the  first  case  we  had  the  laboratory  separation  of  D, 
from  the  lines  5048,  5016,  and  4922. 

Later  on  in  the  same  month  I  showed  that  the  lines  at 
D3  and  447  behaved  in  one  way,  and  that  at  667  behaved 
in  another. 

In  order  to  test  this  view  I  made  some  observations 
based  on  the  following  considerations  : — 

(1)  In  a  simple  gas  like  hydrogen,  when  the  tension  of 
the  electric  current  given  by  an  induction  coil   is  increased 


274  SCIENCE  PROGRESS. 

by  inserting  first  a  jar  and  then  an  air-break  into  the  circuit, 
the  effect  is  to  increase  the  brilliancy  and  the  breadth  of  all 
the  lines,  the  brilliancy  and  breadth  being  greatest  when  the 
longest  air-break  is  used. 

(2)  Contrariwise,  when  we  are  dealing  with  a  known 
compound  gas ;  at  the  lowest  tension  we  may  get  the 
complete  spectrum  of  the  compound  without  any  trace  of 
its  constituents,  and  we  may  then,  by  increasing  the  tension, 
gradually  bring  in  the  lines  of  the  constituents,  until,  when 
complete  dissociation  is  finally  reached,  the  spectrum  of  the 
compound  itself  disappears. 

Working  on  these  lines  the  spectrum  of  the  spark  at 
atmospheric  pressure  passing  through  the  gas  or  gases, 
distilled  from  broggerite,  has  been  studied  with  reference 
to  the  special  lines  C  (hydrogen),  D3,  667,  and  447. 

The  first  result  is  that  all  the  lines  do  not  vary  equally 
as  they  should  do  if  we  were  dealing  with  a  simple  gas. 

The  second  result  is  that  at  the  lowest  tension  667  is 
relatively  more  brilliant  than  the  other  lines  ;  on  increasing 
the  tension  C  and  D3  considerably  increase  their  brilliancy, 
667  relatively  and  absolutely  becoming  more  feeble,  while 
447,  seen  easily  as  a  narrow  line  at  low  tension,  is  almost 
broadened  out  into  invisibility  as  the  tension  is  increased 
in  some  of  the  tubes,  or  is  greatly  brightened  as  well  as 
broadened  in  others  (Fig.  12). 


4471 

D3 

5875. 

c 

6563  667. 

1. 

Mi 

Fig.  12. — Diagram  showing  changes  in  intensities  of  lines  brought  about  by  varying  the 
tension  of  the  spark,     i.  Without  air-break.     2.  With  air-break. 

The  above  observations  were  made  with  a  battery  of 
five  Grove  cells  ;  the  reduction  of  cells  from  5  to  2  made 
no  difference  in  the  phenomena  except  in  reducing  their 
brilliancy. 

Reasoning  from  the  above  observations  it  seems  evident 
that  the  effect  of  the  higher  tension  is  to  break  up  a  com- 
pound or  compounds,  of  which  C,  D3,  and  447  represent 
constituent  elements ;    while,   at   the  same   time,   it   would 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  275 

appear  that  667  represents  a  line  of  some  compound  which 
is  simultaneously  dissociated. 

The  unequal  behaviour  of  the  lines  has  been  further 
noted  in  another  experiment,  in  which  the  products  of 
distillation  of  broggerite  were  observed  in  a  vacuum  tube 
and  photographed  at  various  stages.  After  the  first  heating 
D3  and  447 1  were  seen  bright,  before  any  lines  other  than 
those  of  carbon  and  hydrogen  made  their  appearance. 
With  continued  heating  667,  5016,  and  492  also  appeared, 
although  there  was  no  notable  increase  of  brightness  in  the 
yellow  line  ;  still  further  heating  introduced  additional  lines, 
5048  and  6347. 

These  changes  are  represented  graphically  in  the  fol- 
lowing diagram  (Fig.  13). 

D3 


447.  492.501.  5876.  634  667. 

504 
Fig.  13. — Diagram  showing  order  in  which  lines  appear  in  spectrum  of  vacuum  tube 

when  broggerite  is  heated. 

It  was  recorded  further  that  the  yellow  line  was  at  times 
dimmed,  while  the  other  lines  were  brightened. 

In  my  second  note,  communicated  to  the  Royal  Society 
on  the  8th  May,  I  stated  that  I  had  never  once  seen  the 
lines  recorded  by  Thalen  in  the  blue,  at  A  4922  and  4715. 

It  now  seems  possible  that  their  absence  from  my 
previous  tubes  was  due  to  the  fact  that  the  heating  of  the 
minerals  was  not  sufficiently  prolonged  to  bring  out  the 
gases  producing  these  lines. 

It  is  perhaps  to  the  similar  high  complexity  of  the  gas 
obtained  from  cleveite  that  the  curious  behaviour  of  a  tube 
which  Professor  Ramsay  was  so  good  as  to  send  me,  must 
be  ascribed.  When  I  received  it  from  him  the  glorious 
yellow  effulgence  of  the  capillary  while  the  current  was 
passing  was  a  sight  to  see.  But  after  this  had  gone  on 
for  some  time,  while  the  coincidence  of  the  yellow  line  with 
D3  of  the  chromosphere  was  being  inquired  into,  the  lumi- 
nosity of  the  tube  was  considerably  reduced,  and  the  colours 


276  SCIENCE  PROGRESS. 

in  the  capillary  and  near  the  poles  were  changed.  From 
the  capillary  there  was  but  a  feeble  glimmer,  not  of  an 
orange  tint,  while  the  orange  tint  was  now  observed  near 
the  poles,  the  poles  themselves  being  obscured  by  a  coating 
on  the  glass  of  brilliant  metallic  lustre. 

After  attempting  in  vain  for  some  time  to  determine  the 
cause  of  the  inversion  of  D3  and  447  in  various  photographs 
I  had  obtained  of  the  spectra  of  the  products  of  distillation 
of  many  minerals,  it  struck  me  that  these  results  might  be 
associated  with  the  phenomena  exhibited  by  the  tube,  and 
that  one  explanation  would  be  rendered  more  probable  if  it 
could  be  shown  that  the  change  in  the  illumination  of  the  tube 
was  due  to  the  formation  of  platinum  compounds,  platinum 
poles  being  used.  On  2 1st  May  I  accordingly  passed  the  cur- 
rent and  heated  one  of  the  poles,  rapidly  changing  its  direction 
to  assure  the  action  of  the  negative  pole,  when  the  capillary 
shortly  gave  a  very  strong  spectrum  of  hydrogen,  both  lines 
and  structure.  A  gentle  heat  was  continued  for  some  time, 
and  apparently  the  pressure  in  the  tube  varied  very  con- 
siderably, for  as  it  cooled  the  hydrogen  disappeared  and  the 
D3  line  shone  out  wTith  its  pristine  brilliancy.  The  experi- 
ment was  repeated  on  24th  May,  and  similar  phenomena 
were  observed. 

Some  little  time  after1  Professors  Runge  and  Paschen, 
from  an  entirely  different  standpoint,  arrived  at  exactly  the 
same  conclusion. 

The  employment  of  exposures  extending  over  seven 
hours  has  given  a  considerable  extension  in  the  number  of 
lines,  and  the  bolometer  has  been  called  in  to  investigate 
lines  in  the  infra-red  ;  better  still,  they  have  employed  well- 
practised  hands  in  searching  for  series  of  lines.  Operating 
by  chemical  means  upon  a  crystal  of  cleveite  free  from  any 
other  mineral,  they  have  obtained  a  product  so  pure  that 
from  these  series  there  are  no  outstanding  lines.  Very 
great  weight,  therefore,  must  be  attached  to  their  conclusions. 

As  a  result  of  their  investigations  Drs.  Runge  and 
Paschen  stated  that  the  gas  given  off  even  by  a  pure  crystal 

1  Nature,  26th  September,  1895. 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  277 

of  cleveite  is  not  simple.  In  their  view  the  mixture  consists 
of  two  constituents. 

This  conclusion  was  arrived  at  from  the  following  con- 
siderations. "  The  wave-lengths  A  of  the  lines  belonging  to 
the  same  series  are  always  approximately  connected  by  a 
formula  somewhat  similar  to  Balmer's — 

i/X  =  A  -  B/;//2  -  C/m\ 

A  determines  the  end  of  the  series  towards  which  the  lines 
approach  for  high  values  of  m,  but  does  not  influence  the 
difference  of  wave-numbers  of  any  two  lines.  B  has  nearly 
the  same  value  for  all  the  series  observed,  and  C  may  be 
said  to  determine  the  spread  of  the  series,  corresponding 
intervals  between  the  wave-numbers  being  larger  for  larger 
values  of  C.  As  B  is  approximately  known  two  wave- 
lengths of  a  series  suffice  to  determine  the  constants  A  and 
C,  and  thus  to  calculate  approximately  the  wave-lengths  of 
the  other  lines.  It  was  by  this  means  that  we  succeeded  in 
disentangling  the  spectrum  of  the  gas  in  cleveite,  and 
showing"  its  regularity. 

"In  the  spectrum  of  many  elements  two  series  have  been 
observed  for  which  A  has  the  same  value,  so  that  they  both 
approach  to  the  same  limit.  In  all  these  cases  the  series 
for  which  C  has  the  smaller  value,  that  is  to  say,  which  has 
the  smaller  spread,  is  the  stronger  of  the  two.  In  the 
spectrum  of  the  gas  in  cleveite  we  have  two  instances  of 
the  same  occurrence.  One  of  the  two  pairs  of  series,  the 
one  to  which  the  strong  yellow  double  line  belongs,  consists 
throughout  of  double  lines  whose  wave-numbers  seem  to  have 
the  same  difference,  while  the  lines  of  the  other  pair  of  series 
appear  to  be  all  single.  Lithium  is  an  instance  of  a  pair  of 
series  of  single  lines  approaching  to  the  same  limit.  But 
there  are  also  many  instances  of  two  series  of  double  lines 
of  equal  difference  of  wave-numbers  ending  at  the  same 
place  as  sodium,  potassium,  aluminium,  etc.  There  are  also 
cases  where  the  members  of  each  series  consist  of  triplets  of 
the  same  difference  of  wave-numbers,  as  in  the  spectrum  of 
magnesium,  calcium,  strontium,  zinc,  cadmium,  mercury. 
But  there  is  no  instance  of  an  element  whose  spectrum 
contains  two  pairs  of  series  ending  at  the  same  place.     This 


278  SCIENCE  PROGRESS. 

suggested  to  us  the  idea  that  the  two  pairs  of  series  belonged 
to  different  elements.  One  of  the  two  pairs  being  by  far 
the  stronger,  we  assume  that  the  stronger  one  of  the  two 
remaining  series  belongs  to  the  same  element  as  the  stronger 
pair.  We  thus  get  two  spectra  consisting  of  three  series 
each,  two  series  ending  at  the  same  place,  and  the  third 
leaping  over  the  first  two  in  large  bounds  and  ending  in  the 
more  refrangible  part  of  the  spectrum.  This  third  series  we 
suppose  to  be  analogous  to  the  so-called  principal  series  in 
the  spectra  of  the  alkalis,  which  show  the  same  features. 
It  is  not  impossible,  one  may  even  say  not  unlikely,  that 
there  are  principal  series  in  the  spectra  of  the  other  elements. 
But  so  far  they  have  not  been  shown  to  exist. 

"  Each  of  our  two  spectra  now  shows  a  close  analogy  to 
the  spectra  of  the  alkalis. 

"We  therefore  believe  the  gas  in  cleveite  to  consist  of 
two,  and  not  more  than  two,  constituents." 

To  the  one  containing  the  line  D3,  which  I  discovered 
in  1868,  the  name  helium  remains  ;  the  other  for  the  present 
we  may  call  "  gas  X  V 

The  chief  lines  of  these  two  constituents  are  as  follows, 
according  to  Runge  and  Paschen,  the  wave-lengths  being 
abridged  to  five  figures. 


i 


Hi  I  ol 


I  II]  L 

8 
If  ' 


i     ! 

~'^r 

r  5 

1L 

Li 

,r  in. 

1 

j  A 

•    .1 

' 

ttSTtTUCHY  ■  CAS 

1 

j 

i 

\ 
1 
J                 _ 

i 
i 

! 

i 

j 

i 

'-' 

j 

"**     ' 

i 

Fig.  14. — Runge  and  Paschen's  results  suggesting  that  cleveite  gives  off 
two  gases,  each  with  three  series  of  lines. 

1  In  the  many  comparisons  I  had  to  make,  I  soon  found  the  incon- 
venience of  not  having  a  name  for  the  gas  which  gave  667,  501  and  other 
lines.     When,  therefore,  Professors  Runge  and  Paschen,  who  had  endorsed 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  279 


HELIUM. 


1st  Subordinate 

2nd  Subordinate 

Principal  Series. 

Series. 

Series. 

2663-3 

3456-9? 

3481-6 

2677-2 

3461-4? 

3490-8 

2696-2 

3466-0 

3502-5 

2723-3 

347I-9 

35I7-5 

2763-9 

3479'1 

3537-0 

2829-2 

3487-9 

3563-I 

2945-2 

3498-8 

3733'0 

3187-8 

35I2'6 

3867-6 

3888-8 

353o-6 

4121-0 

3554-6 

4713-3 

3587-4 

7065-5 

3634-4 

3705-1 

3819-8 

4026-3 

4471-6 

5875-8 

GAS  X. 


1st  Subordinate 

1 
and  Subordinate 

Principal  Series. 

Series. 

Series. 

3176-6 

3756-2 

3770-7 

3196-8 

3768-9 

3787-6 

3211-6 

3785-o 

3838-2 

323I*3 

3805-9 

3878-3 

3258-3 

3833-7 

3936-0 

3296-9 

3872-0 

4024-1 

3354-7 

3926-7 

4169-1 

3447-7 

4009-4 

44377 

3613-8 

4143-9 

5047-8 

3964-9 

4388-1 

7281-8 

5oi5-7 

4922*1 
6678-4 

my  results,  and  had  extended  them,  called  upon  me,  I  thought  it  right  to 
suggest  to  them  that,  sinking  the  priority  of  my  own  results,  we  should  all 
three  combine  in  suggesting  a  name.  Professor  Runge  (under  date  20th 
October)  wrote  me  :  "  The  inference  that  there  are  two  gases  is  a  spectro- 
scopical  one,  being  based  on  the  investigation  of  the  '  series '.  Now,  though 
we  think  this  basis  quite  sound,  we  must  own  that  the  conclusion  rests  on 
induction.  .  .  .  For  this  reason  we  do  not  want  to  give  a  name  to  '  gas 
X '."  I  have  so  far  suggested  no  name,  though  Orionium  and  Asterium 
have  been  in  my  mind. 


280 


SCIENCE  PROGRESS. 


More  recently  Professor  Ramsay  has  abandoned  his 
view  of  the  simple  nature  of  the  cleveite  gas,  and  states 
that  from  his  experiments  "there  appears  ground  for  the 
supposition  that  helium  is  a  mixture  ".1 

THE  EXISTENCE  OF  THE  NEW  GASES  IN  CELESTIAL  BODIES. 

And  now  comes  the  great  revelation,  and  it  is  this. 
The  majority  of  the  lines  classed  as  unknown  in  the  spectra 
of  the  Orion  nebula,  stars  of  Group  III.  and  the  sun  are 
really  due  to  the  cleveite  gases. 

The  following  table  sets  this  result  out.  It  will  be  seen 
that  of  seventeen  unknown  lines,  twelve  have  been  run  to 
earth. 

COMPARISON  OF  UNKNOWN  {PREVIOUS  TO  HE.  AND  X) 
LINES  IN  ORION  NEBULA  AND  BELLA TRIX. 


Orion  Nebula. 

Bellatrix  and 
Eclipse,  1893. 

Origin. 

Campbell. 

Lockyer. 

3869 

*3869    (7) 

t3867-5 

(Falls 

He. 

3889 

3888    (7) 

3888onHe.) 

He. 

— 

4°i  1     (3) 

4009    (8; 

X 

4026 

4026    (5) 

4026  (10) 

He. 

— 

4042     (1) 

4041     (3) 

Still  Unknown 

4067 

4068    (3) 

4°7°    (3) 

Still  Unknown 

4121 

4121     (1) 

4121-3(7) 

He. 

4H3 

4143    (T) 

4144    (8) 

X 

— 

4168    (1) 

4169    (5) 

X 

4265 

4270    (3) 

4268    (7) 

Still  Unknown 

4389 

439°    (3) 

4389    (8) 

X 

4472 

4472    (7) 

4472  (10) 

He. 

— 

454°    (3) 

454i     (1) 

Still  Unknown 

— 

4628    (3) 

4630    (3) 

Still  Unknown 

4714 

47i6    (3) 

47i5    (5) 

He. 

■ — 

*4924    (5) 

f4922-i  (8) 

X 

5874 

5875-8 

5875-8 

D3              He. 

*  Between  these  AA  there  are  forty-two  lines  in  the  Orion  photograph  of  which  six  are 
known  other  than  He.  and  X. 

t  Between  these  AA  there  are  forty-five  lines  in  the  Bellatrix  photograph  of  which 
five  are  known  other  than  He.  and  X. 

The  following  tables   give    the    complete   list  of  lines 
and  the  celestial  body  in  which  they  have  been  traced. 


1  Nature,  vol.  liii.,  p.  598. 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  281 

In  the  tables,  under  "sun,"  C,  followed  by  a  number, 
indicates  the  frequency  as  given  by  Young  ;  E  indicates  the 
lines  photographed  during  the  eclipse  of  1893.  Under 
"star  or  nebula"  the  references  are  to  the  tables  given  in 
my  memoir  on  the  nebula  of  Orion  {Phil.  Trans.,  vol. 
clxxxvi.,  1895,  P-  86  et  seq.      N  =  Nebula  of  Orion). 


HELIUM. 

I 1220. 

Sun. 

Star  or  Nebula. 

3889 

C     E 

N.  III.  y 

3188 

2945 

2829 

2764 

'* 

2723 

2696 

2677 

5876 

C  100  E 

4472 

C  100  E 

4026 

C  25  E 

3820 

E 

a  Cygni 

3705^ 

3634 

3537 

3555 

35I3 

3499 

>* 

3488 

3479 

3472 

3466 

346iy 

7066 

C  100 

47i3 

C  2   E 

4121 

E 

N.  a  Cygni 

3868 

? 

3777 

E 

Bellatrix 

3652 

3599 

3567 

3537 

35i7 

'* 

35°3 

349i 

3482, 

*  Means  that  these  lines  are  out  of  the  range  of  my  observations. 

20 


282 


SCIENCE  PROGRESS. 


GASX. 


Sun. 

Star  or  Nebula. 

5016 

C    30    E 

3965 

? 

III.  y 

36M> 

E 

3448 

3355 

3297 

.* 

3258 

3231 

32i3J 

6678 

C    25 

4922 

C    30    E 

4388 

E 

N.   III.   y 

4144 

E 

III.  y 

4009 

III.  y 

3927 

Bellatrix 

3872 

Bellatrix 

3833 

E 

Hid  byH.  line 

3806 

Bellatrix 

3785* 

7282 

5048 

C    2 

4438 

Bellatrix 

4169 

Bellatrix 

4024 

? 

N.  III.  y 

3936 

Hid  in  K. 

3878 

C           E 

a  Cygni 

3838 

C          E 

a  Cygni 

3803"- 

*  Means  that  these  lines  are  out  of  the  range  of  my  observations. 


The  annexed  reproduction  of  a  photograph  of  Bellatrix 
will  show  how  striking  has  been  the  result  of  the  discovery 
so  far  as  stellar  spectra  are  concerned. 

Hydrogen,  helium  and  gas  X  are  thus  proved  to  be 
those  elements  which  are,  we  may  say,  completely  repre- 
sented in  the  hottest  stars  and  in  the  hottest  part  of  the 
sun  that  we  can  get  at.  Here  then,  in  1895,  we  have 
abundant  confirmation  of  the  views  I  put  forward  in 
1868  as  to  the  close  connection  between  helium  and 
hydrogen. 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  283 

EFFECTS  OF  DIFFUSION. 

A  diffusion  experiment  described  in  their  paper  enabled 
Messrs.  Runge  and   Paschen  to  go  a  stage  farther,  and  to 


x 


a 


31 

0 

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announce  that  of  their  two  constituents  the  gas-giving  D3 
was  the  heavier  one.      They  also  add  :— 

"  From  the  fact  that  the  second  set  of  series  is  on  the 


284  SCIENCE  PROGRESS. 

whole  situated  more  to  the  refrangible  part  of  the  spectrum, 
one  may,  independently  of  the  diffusion  experiment,  con- 
clude that  the  element  corresponding  to  the  second  set  is  the 
heavier  of  the  two  ". 

As  they  themselves  pointed  out,  however,  the  result  was 
not  final,  because  the  pressures  were  not  the  same.  I  have 
recently  made  some  experiments  in  which  the  pressures 
remain  the  same. 

An  U  tube  was  taken,  and  at  the  bend  was  fixed  a 
plaster  of  Paris  plug  about  1*5  cm.  thick;  in  one  of  the 
limbs  two  platinum  wires  were  inserted.  The  plug  was 
saturated  with  hydrogen  to  free  it  from  air  ;  the  tube  was 
then  plunged  into  a  mercury  trough,  and  fixed  upright  with 
the  limbs  full  of  mercury.  Into  the  leg  (A)  with  the  plati- 
num wires  a  small  quantity  of  hydrogen  was  passed,  and  as 
soon  after  as  possible  another  small  quantity  of  a  mixture 
of  helium  and  hydrogen  from  samarskite  was  put  up  the 
other  limb  (B)  of  the  U  tube. 

Immediately  after  the  helium  was  passed  into  the  limb 
(B)  spectroscopic  observations  were  made  of  the  gas  in  the 
limb  (A) ;  D3  was  already  visible,  and  there  was  no  trace  of 
50157.  This  result  seems  to  clearly  indicate  that  if  a  true 
diffusion  of  one  constituent  takes  place,  the  component  which 
gives  D3  is  lighter  than  the  one  which  gives  the  lines  at 
wave-length  50157. 

Although  this  result  is  opposed  to  the  statement  made 
by  Runge  and  Paschen,  it  is  entirely  in  harmony  with  the 
solar  and  stellar  results. 

In  support  of  this  I  may  instance  that  of  the  cleveite 
lines  associated  with  hydrogen  in  the  chromosphere  and  the 
stars  of  Group  III.  y ;  those  allied  to  D3  are  much  stronger 
than  those  belonging  to  the  series  of  which  50157  forms 
part. 

MINERALS  EXAMINED. 

So  far  I  have  worked  upon  some  seventy  minerals,  and 
I  have  found  the  orange  line  in  sixteen. 

The  following  are  the  minerals,  etc.,  which  have  been 


THE  GROWTH  OF  OUR  KNOWLEDGE  OF  HELIUM.  285 

investigated  ;  those  which  give  the  D.  line  beino-  marked 
with  an  asterisk  : — 


*.Eschynite. 

Almandine. 

Anglesite. 

Anhydrite. 

Augite. 

Barytes. 
*Broggerite. 

Bronzite. 

Calco-uranite. 

Cassiterite. 

Celestine. 

Chalk. 

Charnockite. 

Chromite. 
*Cleveite. 

Columbke. 

Crocidolite. 

Cupro-uranite. 
*Eliasite. 

Enstatite. 
*Euxenite. 
*Fergusonite. 

Franklinite. 

Gadolinite. 

Gahnite. 

Geikielite. 

Gneiss. 

Granite. 

Graphite. 
*Gummite. 

Haematite. 
*Hielmite. 

Hornblende. 

Hypersthene. 

Ilmenite. 


Iridosmine. 
Kielhanite. 

Kyanite. 

Ludvvigite. 

Magnesium. 

Magnetite. 

Manganese  Nodule. 

Minium. 
*Monazite. 

Obsidian. 

Olivine. 

Olivine-Enstatite. 
*Orangeite. 

Orthite. 

Pitchblende. 

Plumbic  Ochre. 
*Polycrase. 
*Pyrochlore. 

Quartz. 

Red  Clay. 

Rhodonite. 
*Samarskite. 

Schurlomite. 

Sphene. 

Staurolite. 

Thorite. 
*Thoro-gummite. 
*Uraninite. 

Uranocircite. 

Uranophase. 

Wulfenite. 

Wolfram. 

Xenotine. 
*Yttro-Gummite. 


J.   Norman   Lockyer. 


INSULAR  FLORAS. 

PART  VI.  (a). 

IN  the  preceding  articles  I  have  briefly  reviewed  the 
literature  relating  to  Insular  Floras  which  has  appeared 
during  the  last  decade,  and  I  have  extracted  therefrom  the 
principal  or  most  interesting  facts,  which  I  have  given  with 
some  comments  of  my  own.  That  I  have  been  able  to  do 
this  with  some  profit  is  largely  due  to  the  advantages  I  have 
enjoyed  through  the  kindness  of  the  Director  of  the  Royal 
Gardens,  Kew.  Since  the  publication  in  1885  of  my  first 
essay  on  this  subject,  in  the  Botany  of the  Voyage  of  H.  M.S. 
"  Challenger"  all  or  nearly  all  collections  of  insular  plants 
received  at  Kew  have  passed  through  my  hands  for  determina- 
tion and  reporting  on  ;  and  I  have  also  been  favoured  with 
many  notes  and  criticisms  by  travellers  and  other  persons 
interested  in  plant  distribution.  I  propose  therefore  to 
enter  into  a  short  recapitulation  and  discussion  of  the  main 
facts  thus  accumulated  ;  but  before  doing-  so  I  will  refer  to 
some  more  or  less  important  contributions  to  the  subject 
that  have  come  to  light  during  the  progress  of  the  present 
series  of  articles.1 

It  will  be  convenient  to  take  the  islands  in  the  same 
geographical  order  previously  followed  (1),  beginning  with 
Polynesia. 

There  are  some  interesting  recent  contributions  to  the 
flora  of  Polynesia,  taking  the  designation  in  its  widest 
sense  ;  but  no  one  has  yet  attempted  to  bring  together  what  is 
known,  or  ascertainable  from  materials  preserved  in  herbaria, 
of  the  vegetation  of  the  numerous  small  coral  islands  and 
groups  of  islands,  more  or  less  recently  annexed  by,  or  taken 
under  the  protection  of,  Great  Britain.  This  the  writer  is 
engaged  upon,  and  some  particulars  thus  acquired  may  be 

1  A  review  of  the  additional  literature  having  extended  beyond  what 
was  expected,  the  discussion  referred  to  will  form  the  subject  of  a  conclud- 
ing article. 


INSULAR  FLORAS.  287 

utilised  here  in  dealing  with  the  literature  of  the  subject. 
Some  years  ago  Mr.  J.  T.  Arundel  delivered  a  lecture  at 
San  Francisco,  before  the  Geographical  Society  of  the 
Pacific,  on  the  Phcenix  Group  and  other  islands  of  the 
Pacific,  and  he  has  since  published  it  (2)  with  additional 
notes.  Mr.  Arundel  writes  from  actual  experience,  having 
visited  a  large  number  of  the  most  remote  islets  of  the 
Pacific  and  collected  samples  of  their  scanty  floras,  which 
were  determined  for  him  at  Kew,  where  the  specimens  are 
preserved.  Unfortunately  several  of  the  names  of  the 
plants  in  his  list  have  undergone  such  a  transformation  as 
to  be  almost  unrecognisable. 

Besides  the  Phcenix  Group,  which  was  under  his  personal 
control,  Mr.  Arundel  visited  such  out-of-the-way  islands  as 
Starbuck,  Caroline  (not  the  Caroline  Group),  Fanning, 
Maiden,  Palmerston  and  Ducie.  Mr.  Arundel  describes 
Starbuck  and  Caroline  Islands  as  examples  of  two  kinds  of 
very  small  islands  common  in  the  Pacific,  though  not  con- 
fined to  it.  The  former  represents  those  consisting  of  an 
unbroken  mass  which  is  treeless,  and  indeed  almost  devoid 
of  vegetation  ;  and  the  latter  is  a  typical  coral  atoll,  con- 
sisting of  a  ring  of  islets  encircling  a  central  lagoon,  and 
supporting  a  relatively  luxuriant  vegetation.  Starbuck  is 
very  scantily  furnished  with  vegetation,  only  about  half  a 
dozen  species  being  represented.  The  principal  plants  are 
Lepidium  piscidium  and  Sida  fallax ;  both  of  wide  range 
in  Polynesia.  Caroline  Island  claims  a  little  more  atten- 
tion, because  its  history,  position,  conformation,  meteorology, 
botany  and  zoology  have  been  very  fully  worked  out  and 
illustrated.  In  1883  this  island  was  selected  by  the  Ameri- 
cans, by  the  British,  and  by  the  French  as  the  most  suitable 
spot  for  observing  the  total  eclipse  of  the  sun.  The  Ameri- 
can party  was  relatively  numerous,  and  they  drew  up  a 
somewhat  elaborate  report  (3),  illustrated  chiefly  by  prints 
from  photographs  taken  by  the  two  gentlemen  constituting 
the  English  party.  These  illustrations  give  an  excellent 
idea  of  the  form  and  vegetation  of  an  atoll,  including  a 
bird's  eye  view,  which  enables  us,  better  than  any  description 
could,  to  realise  its  smallness  and  isolation.      Caroline  Island 


288  SCIENCE  PROGRESS. 

is  situated  in  almost  exactly  150°  W.  longitude  and  io°  S. 
latitude,  and  is  distant,  according  to  Mr.  Arundel,  about 
400  miles  from  Tahiti,  the  nearest  island  of  considerable 
size — say  a  third  larger  than  the  Isle  of  Wight ;  and  420 
from  Starbuck.  Although  in  most  parts  well  clothed  with 
vegetation,  this  vegetation  consists  of  very  few,  perhaps 
not  more  than  twenty,  species  of  vascular  plants.  Several 
others  now  exist,  either  as  the  remains  of  cultivation  or 
accidental  introduction  ;  and  the  abundance  of  the  cocoanut 
palm  is  due  to  planting,  which  has  now  been  in  operation 
for  some  years.  Whether  the  cocoanut  existed  in  the 
island  on  the  first  advent  of  man  there  is  no  evidence  to 
show  ;  but  there  are  trees  of  other  kinds  of  large  size,  as 
depicted  and  described  in  the  report  referred  to.  They  are: 
Calophyllum  Inophylliim  (Guttiferse),  Morinda  citrifolia 
(Rubiaceae),  Cordia  subcordata  (Boragineae),  Pisonia  grandis 
(Nyetaginaceae),  and  a  screw  pine,  probably  the  widely  spread 
Pandanus  odoratissi?nus.  One  of  the  illustrations  is  a  most 
effective  representation  of  a  group  of  screw  pines.  The 
Cordia  is  perhaps  the  commonest  tree,  and  is  most  con- 
spicuous, having  a  spreading  crown  with  branches  down  to 
the  ground.  Pisojiia  grandis  is  described  as  forty  or  fifty 
feet  high,  with  a  trunk  four  feet  in  diameter ;  dimensions 
one  would  hardly  have  expected.  I  have  drawn  some- 
what freely  from  this  report,  because  it  is  by  far  the  most 
instructive  known  to   me. 

A  more  recent  contribution  to  island  literature  by  Mr. 
C.  M.  Woodford  (4)  is  equally  deserving  of  attention, 
though  wanting  illustrations.  It  deals  with  the  Gilbert 
Archipelago,  one  of  the  most  remarkable  of  the  numerous 
groups  in  the  Eastern  Pacific.  There  are  sixteen  islands, 
not  counting  the  islets  of  the  atolls,  forming  a  chain,  trend- 
ing from  north-west  to  south-east  and  extending  from  about 
3°  north  to  30  south  latitude  in  1730  to  1 77°  east  longitude. 
Eleven  out  of  the  sixteen  are  of  atoll  formation,  and  the 
largest  of  them  is  little  more  than  twenty  miles  long  and 
twenty  feet  high  in  the  highest  part.  They  are  mostly 
inhabited,  and  the  population  half  a  century  ago  was 
estimated  at  50,000,  though  it  has  since  dwindled  down  to 


INSULAR  FLORAS.  289 

probably  a  quarter  of  that  number.  The  presence  of  so 
large  a  population  must  have  had  some  modifying  influence 
on  the  vegetation  ;  yet  not  to  the  extent  that  might  have 
been  expected,  because  there  is  little  cultivation,  the  natives 
living  largely  on  fish,  with  which  the  waters  swarm.  Mr. 
Woodford  says  :  "  The  islands  are  clothed  from  end  to  end 
with  a  dense  growth  of  cocoanut  palms  and  other  vegeta- 
tion, and  present  a  beautiful  appearance  when  approaching 
from  the  sea.  The  reefs  and  lagoons  teem  with  fish,  thus 
enabling  the  islands  to  support  a  population  which  for 
their  land  area  was  at  one  time  equalled  in  no  part  ot  the 
world." 

Mr.  Woodford  gives  a  list  of  the  plants  compiled  from 
observations  on  the  islands  he  visited,  which  he  believes  is 
nearly  complete.  As  I  am  able  to  supplement  it  by  a  few 
additional  species  in  the  Kew  Herbarium,  chiefly  collected 
by  the  Rev.  Mr.  Whitmee,  and  also  to  supply  specific  names 
in  some  cases  where  he  gives  only  the  generic,  I  will  give  a 
list  of  all  the  vascular  plants  known  to  inhabit  the  group,  as 
a  sample  of  the  typical  coral  island  flora.  Calopkyllum 
Inophyllum  (Guttiferae),  Sidafallax  (Malvaceae),  Triiunfetta 
procumbens  (Tiliaceae),  Tribulus  cistoides  (Zygophyllacese), 
Pemphis  acidula  (Lytheraceae),  Rhizophora  mubronata 
(Rhizophoraceae),  Guettarda  speciosa  and  Morinda  citrifolia 
(Rubiaceae),  Sccevola  Kcenigii  (Goodeniaceae),  Tournefortia 
argentea  (Boraginaceae),  Pisonia  biennis  and  Boerhaavia 
^fksYZ  (Nyctaginaceae),  Euphorbia  Atoto?  (Euphorbiaceae), 
Ficus  tinctoria  (Moraceae),  Crinum  pedunculatum  ?  (Am- 
aryllidaceae),  Cocos  nucifera  (Palmaceae),  Pandanus  odora- 
tissimus  (Pandanaceae),  Fimbristylis  glomerata  (Cyperaceae), 
Lepturus  repens  (Gramineae),  and  Polypodium  Phymatodes 
(Filices) — just  a  score  of  species,  it  will  be  seen,  belonging 
to  as  many  different  genera,  and  to  eighteen  different  natural 
'orders  of  the  most  diverse  habit  and  structure.  They 
are  almost  without  exception  plants  of  general  distribution 
in  tropical  oceanic  islands  and  on  the  sea-shores  of  the 
continents.  The  majority  of  them  indeed  inhabit  the 
smaller  remote  islands  of  the  tropical  parts  of  the  Indian 
Ocean.      I  will  only  add  here  that  their  seeds  are  such  as 


2go  SCIENCE  PROGRESS. 

are  transported  by  oceanic  currents,  birds,  and  winds,  with- 
out destroying  their  vitality.  In  another  article  I  pro- 
pose discussing  these  agents  of  dispersal  in  some  detail. 
The  absence  from  the  above  list  of  the  two  largest  natural 
orders — Leguminosae  and  Compositse — may  cause  some 
surprise,  especially  as  the  seeds  of  many  of  the  former  bear 
long  immersion  in  salt  water  with  impunity,  and  the  pappose 
achenes  of  the  latter  are  often,  it  is  assumed,  conveved 
lont{  distances  bv  wind.  Le^uminos£e  are  rare  in  all 
oceanic  islands,  both  coral  and  volcanic  ;  but  Composite, 
on  the  other  hand,  are  characteristic  of  many  volcanic 
islands,  the  Galapagos  and  St.  Helena,  for  example. 

The  distribution  of  the  plants  of  the  Tonga  or  Friendly 
Islands  has  been  worked  out  by  the  writer  (5),  and  a  few 
of  the  most    interesting  facts  may  be  repeated  here.      This 
group  lies   to  the  south-east  of  Fiji,    between   180  and  230 
south  latitude,  and  1730  and  176°  west  longitude,  and  com- 
prises both  volcanic  and  coral  islands  ;  some  of  the  former 
being  considerably  larger  than  those  of  the  Gilbert  Group, 
and  rise  to  altitudes  of  500  to   3000  feet.      Fuller  informa- 
tion on  the  geology  of  the  islands  will  be  found  in  an  article 
(6)  by  Mr.    J.   J.  Lister.      But  although  the  Tonga  Islands 
are  considerably  larger  than   the  Gilbert  Islands,  it   is  more 
in   land   area   and  altitude    than   external   dimensions,   and 
it  is  due  partly  to  the  absence   of  central  lagoons.      Ton- 
gatabu   in    the    south,  the    largest    of   the   group,   is   about 
twenty-two    miles  in   its  greatest   length,  and  is  composed 
entirely  of  coral  limestone.      This  island  is   the  best  known 
botanically ;  but    Mr.    ].  J.    Lister,    whose   collections   were 
worked  out  for  my  paper  referred  to  above,  thoroughly  ex- 
plored  the    neighbouring    smaller,    though   more    elevated, 
Eua,    which   gave    a    considerable    number    of    additional 
species.       Since   the    publication   of  my   paper,    Kew    has 
acquired  a  collection  of  dried   plants  made  by  Mr.   C.    S. 
Crosby  in  the  Vavau  cluster  in   the  north.      This  collection 
has   not    yet    been    thoroughly   worked    out,   but  although 
it  doubtless  contains  some  additions,  they  will  not  be  of  a 
character  to   modify  what  has   been   written  respecting  the 
affinities  of  the  flora  of  the  whole  group.      The  total  num- 


INSULAR  FLORAS.  291 

ber  of  assumed  indigenous  species  of  vascular  plants  in 
my  enumeration  is  290,  whereof  246  have  a  westward,  and 
220  have  an  eastward  extension  in  Polynesia;  138  are 
Australasian  (Australia,  New  Zealand  and  outlying  islands), 
162  are  Malayan,  and  at  least  150  have  a  wider  range 
either  in  the  Old  or  New  World,  or  in  both.  From  the 
foregoing  figures  it  will  be  seen  that  the  Bora  of  the 
Tonga  Islands  is  largely  composed,  like  the  very  small  one 
of  the  Gilbert  Islands,  of  species  of  wide  distribution. 
Indeed  no  genus  is  peculiar  to  the  group,  and  only  ten 
species  so  far  as  our  present  knowledge  goes  are  endemic, 
and  a  more  complete  exploration  of  the  Fiji  Islands  and 
other  neighbouring  groups  may  reduce  this  number.  The 
290  species  of  the  Tongan  flora  represent  no  fewer  than 
202  genera  and  seventy-nine  natural  orders  out  of  the  202 
recognised  in  Bentham  and  Hooker's  Genera  Plantarum. 
The  proportions  are  2*55  genera  to  an  order,  and  1  '43  species 
to  a  genus  in  the  Tongan  flora.  In  the  flora  of  the  world 
the  proportions  I  obtained  by  a  very  rough  calculation  are 
37 '5°  genera  to  an  order,  and  12*65  species  to  a  genus. 
Taking  the  number  of  Tongan  species  (138)  which  extend 
to  Australasia,  one  might  overestimate  the  affinities,  be- 
cause, as  a  matter  of  fact,  a  large  proportion  of  these  species 
have  a  wide  range.  Indeed  only  a  dozen  species  have 
decidedly  Australasian  connections.  These  are  :  Melicytus 
ramiflorus,  Ratonia  stipitata,  Metrosideros  polymorpha, 
Jasmirmm  simplicifolium,  Hoya  australis,  Iponuea  congesta, 
Pisonia  inermis,  Peperomia  leptostackya,  Euphorbia  Spar- 
mannii,  Ficus  aspera,  Podocarpus  elata  and  Pteris  comans. 
It  will  be  perceived  that  the  connections  are  specific  rather 
than  generic.  But  the  most  significant  facts  brought  out 
in  the  paper  under  consideration  are  two,  namely,  the 
large  proportion  of  species — upwards  of  a  third — peculiar  to 
Polynesia,  and  the  strongly  Malayan  character  of  the  flora, 
generally,  of  the  Tonga,  Fiji  and  Samoa  Islands. 

Several  additional  small  contributions  to  the  flora  of 
the  Solomon  Islands  have  appeared  (7),  including  some 
highly  interesting  novelties  collected  by  the  officers  of 
H.M.S.  Penguin,  and  the  Rev.   R.   B.  Comins.      Excellent 


292  SCIENCE  PROGRESS. 

photographs  of  the  singular  new  genus  Sararanga 
(Pandanaceae)  have  been  received  at  Kew,  as  well  as  ripe 
fruit  in  spirit,  which  will  enable  me  to  add  to  my  published 
description,  though  not  to  complete  it,  because  the  male 
inflorescence  is  still  unknown.  Two  species  of  Begonia,  an 
Oxymitra  (Anonacese)  with  flowers  nearly  nine  inches  long, 
a  singular  Tabernce  Montana  having  a  twisted  fruit,  and 
the  anomalous  genus  Lophopyxis  (8)  are  among  the  latest 
additions  to  the  flora  of  the  Solomon  Islands.  The  last  is 
doubtingly  placed  in  the  Euphorbiaceae  by  Sir  Joseph 
Hooker,  and  it  has  since  been  twice  described  (9  and  10), 
and  placed  in  different  natural  orders,  namely,  Combretopsis 
(Olacinese)  and  Treubia  (Saxifragaceae).  There  are  two 
or  three  very  closely  allied  species  or  races  inhabiting 
Malacca,  Ceram,  New  Guinea,  and  the  Solomon  Islands. 
I  may  refer  in  passing  to  a  zoological  paper  (11)  in  which 
the  author  puts  forward  the  theory  of  a  former  connection 
of  the  Solomon,  Fiji,  New  Hebrides,  Loyalty,  New- 
Caledonia,  Norfolk  and  New  Zealand  Islands  with  New 
Guinea,  but  not  with  Australia.  That  there  was,  in  the 
remote  past,  a  greater  land  area  in  this  region  seems 
highly  probable,  but  the  relationships  are  so  complex  that 
fuller  data  are  required  to  afford  a  solution  of  the  problem. 
The  present  flora  of  Lord  Howe  Island,  described  a  few 
pages  forward,  does  not  favour  Mr.  Hedley's  views  in  their 
entirety  on  this  point. 

In  my  reference  to  the  flora  of  Christmas  Island  (12)  I 
overlooked  a  paper  that  supplemented  mine  to  some  extent 
(13),  especially  in  relation  to  the  vegetation. 

Dr.  Trimen  (14)  has  published  two  more  volumes  of 
his  admirable  flora  of  Ceylon,  bringing  it  down  to  the  end 
of  the  Balanophoraceae,  following  the  arrangement  of 
Bentham  and  Hooker's  Genera  Plantarum.  The  same 
author  has  drawn  up  a  provisional  list  (15)  of  Maldive 
plants  ;  the  first,  I  believe,  that  has  appeared.  As  might 
be  expected  there  is  no  endemic  element,  and  the  vegeta- 
tion is  an  assemblage  of  the  ubiquitous  coral  island  plants 
and  weeds  of  cultivation.  Dr.  Trimen  makes  no  mention  of 
the  Cocos  maldivica  or  Coco-de-mer  (Lodoicea  sey  die  liar  inn)  \ 


INSULAR  FLORAS.  293 

but,  although  it  is  improbable  that  this  palm  ever  grew  in 
the  Maldive  Islands,  something  yet  remains  to  be  done  to 
complete  its  history.  John  de  Barros,  a  Portuguese 
author,  is  thus  quoted  (16)  by  the  writer  of  an  article  on 
these  islands  : — 

"Their  productions  he  also  enumerates  minutely, especially 
the  coconut,  both  of  the  ordinary  kind  and  of  that  called 
coco-de-mer,  almost  peculiar  to  the  Seychelles,  the  seed  of 
which  appears  to  have  been  borne  thence  to  the  Maldivas 
by  the  currents  of  the  ocean  ". 

Since  the  publication  of  my  notes  on  the  flora  of  New 
Zealand  and  the  outlying  islands  (17)  several  interesting 
papers  on  the  subject  have  appeared,  though  there  is  only 
one  of  sufficient  importance  to  call  for  more  than  brief 
mention.  But  first  the  minor  ones.  Mr.  F.  Kirk  is  the 
author  (18)  of  a  series  of  monographs  treating  of  the 
genera  Gentiaua,  Colobatttktis,  and  Gunnera,  as  re- 
presented in  the  New  Zealand  region,  besides  descriptions 
of  a  number  of  new  species  belonging  to  various  natural 
orders.  The  forms  of  Gentiana  are  numerous,  and  the 
species  exceedingly  difficult  of  delimitation.  Kirk  defines 
ten  species,  and  about  half  of  them  comprise  several 
varieties.  They  are  spread  all  over  New  Zealand,  except 
the  extreme  north,  and  they  extend  to  the  Chatham, 
Antipodes,  Auckland  and  Campbell  Islands  ;  but  hitherto 
no  species  has  been  found  in  Macquarie  Island,  the  southern- 
most of  these  islands.  They  chiefly  inhabit  the  mountains, 
in  alpine  and  subalpine  situations,  and  the  sea-coast  ;  four 
out  of  the  ten,  it  is  stated,  not  being  found  out  of  the  reach 
of  the  sea-spray.  They  all  belong  to  one  group,  char- 
acterised by  having  pentamerous  flowers,  unappendaged 
corollas,  and  versatile  anthers.  White  is  the  prevailing 
colour  of  all  the  species,  though  some  of  them  occasionally 
exhibit  various  shades,  mostly  dull,  of  red,  purple,  and  violet, 
and  more  rarely  a  pale  yellow.  This  is  in  direct  contrast  to 
the  behaviour  of  the  northern  species,  speaking  generally,  and 
we  are  indebted  to  Mr.  Kirk  for  the  observation.  Colo- 
banthus  (Caryophyllaceae)  is  one  of  those  densely  tufted 
moss-like   genera   of   which    there    are    representatives    in 


294  SCIENCE  PROGRESS. 

various  natural  orders.  It  is  one  of  the  very  few  genera 
common  to  Australasia,  to  the  Antarctic,  and  other  southern 
islands,  and  the  Andes,  and  confined  to  these  regions.  One 
species,  C.  quitensis,  ranges  from  the  mountains  of  Mexico 
to  Cape  Horn  and  reappears  in  New  Zealand.  Kirk  also 
records  it  from  Amsterdam  Island,  but  that  seems  to  in- 
volve two  errors,  for,  so  far  as  our  data  at  Kew  go,  C. 
diffusus  inhabits  St.  Paul,  and  no  species  is  found  in  the 
neighbouring  island  of  Amsterdam.  One  species,  C. 
Billardieri,  is  found  in  the  Alps  of  Victoria,  in  Tasmania,  New 
Zealand,  and  the  small  islands  southward  to  Macquarie.  Two 
Falkland  Islands  species  also  recur  in  South  Georgia,  the 
southern  insular  limit  of  phanerogamic  vegetation  in  the  Pata- 
gonian  region,  if  we  except  a  grass,  Aira  antarctica,  collected 
by  Dr.  Eights  in  the  South  Shetlands,  about  620  S.  lat.,  or 
8°  south  of  South  Georgia.  Kirk  enumerates  and  de- 
scribes ten  species  of  Colobanthas  from  the  New  Zealand 
region,  including  four  proposed  new  ones. 

Gunnera  (Haloragidacea^)  has  a  similar  range  to  that 
of  Colobantkus,  save  that  it  does  not  reach  the  colder  limits 
either  in  America  or  the  New  Zealand  region.  Kirk 
brings  up  the  species  of  the  latter  region  to  nine,  four  of 
which  are  new. 

W.  Colenso,  D.  Petrie,  and  H.  C.  Field  also  describe 
a  few  novelties  (19),  and  the  first  named  gives  a  charming 
description  of  his  travels  and  botanising  in  the  romantic 
country  around  Hawke's  Bay,  upwards  of  fifty  years 
ago. 

The  one  paper  which  I  propose  to  discuss  a  little  more 
in  detail  is  devoted  to  the  natural  history  of  Macquarie 
Island  (20),  the  most  southerly  speck  of  land  in  the  New  Zea- 
land region  known  to  support  phanerogamic  vegetation.  It 
is  in  the  same  latitude  (540  S.)  as  South  Georgia  in  American 
waters,  the  flora  of  which  I  have  described  (21),  where  a 
list  is  given  of  the  vascular  plants  inhabiting  the  island. 
They  are  separated  from  each  other  by  about  164°  of 
longitude,  which  in  this  latitude  means,  in  round  numbers, 
5875  geographical  miles ;  yet,  as  previously  stated,  nine 
out    of   thirteen    of   the    vascular    plants    found    in     South 


INSULAR  FLORAS.  295 

Georgia  also  occur  in  some  of  the  southern  islands  in  the 
New  Zealand  region.  Later  on  I  shall  have  something- 
to  say,  or  rather  repeat,  in  explanation  of  this  fact.  It 
should  be  noted  that  these  islands  are  in  about  the  same 
latitude  as  York  in  England  ;  yet  the  climate  is  now  so 
severe  in  South  Georgia  and  other  conditions  are  so  un- 
favourable to  vegetation  that  the  flora  is  perhaps  poorer 
than  in  the  highest  northern  latitudes  yet  explored,  and 
entirely  wanting  the  colour  characteristic  of  many  northern 
flowers.  For  example,  such  charmingly  beautiful  plants  as 
Papaver  nudicaule,  Silene  acaulis,  Saxifraga  oppositifolia 
and  Epilobium  latifolium  are  found  north  of  the  eightieth 
parallel ;  whereas  the  showiest  flowers  in  South  Georgia  are 
those  of  a  very  small  buttercup,  so  small  indeed  that  they  want 
finding.  The  flora  of  Macquarie  Island  is,  however,  not 
altogether  devoid  of  colour,  as  witness  Pleurophyllum  ;  and 
Stilbocarpa  is  remarkable  for  its  large  rhubarb-like  leaves. 

Macquarie  Island  is  between  twenty  and  twenty-five 
miles  long  and  five  or  six  miles  across  in  its  broadest  part. 
It  is  generally  hilly,  though  the  hills  are  nowhere  above 
800  feet.  The  following  is  a  list  of  the  vascular  plants 
recorded  by  Mr.  Hamilton  (20),  who  visited  the  island 
early  in  1894.  I  may  mention  that  I  had  most  of  these 
plants  under  observation  (22),  and  I  do  not  agree  in  every 
instance  with  his  and  Mr.  Kirk's  (23)  determinations  ;  but 
the  divergencies  are  unimportant ;  and  there  are  several 
corrections  of  the  names  given  in  previously  published  lists. 
Ranunculus  ci-assipes,  Cardaminc  hirsuta,  var.  corymbosa, 
Colobanthus  muscoides,  C.  Billardieri,  Stellaria  decipiens, 
Mont  ia  font  ana,  Aceena  Sanguisorbcz,  A.  adscendens,  Calli- 
triche  a7itarctica.  Epilobium  nummularifolium,  E.  lin- 
nceoides,  Azorella  Selago,  Stilbocarpa  polaris,  Coprosma 
repens,  Cotula  plumosa,  Pleurophyllum  Hookerii,  Uncinia 
nervosa,  Luztila  criuita,  Deschampsia  Hookeri,  D.  penicil- 
lata,  Poa  foliosa,  P.  Hamiltonii,  Agrostis  antarctica, 
Festuca  contracta,  Aspidium  aculeatum,  var.  vest  it  um  Poly- 
podium  aust?'ale,  Lomaria  alpina  and  Lycopodium  Billar- 
dieri, var.  varium.  The  last  named  one  would  have 
hardly  expected  to  find  in   so  high   a  latitude,  where  the 


296  SCIENCE  PROGRESS. 

only  woody  plant  is  the  small  creeping  Coprosma  repens, 
because  it  usually  grows  on  trees.  A  re-examination 
of  a  very  small  collection  of  Macquarie  Island  plants 
sent  by  Mr.  Fraser  of  the  Sydney  Botanic  Garden  to  the 
late  Sir  William  Hooker,  about  sixty  years  ago,  has  led  to 
the  discovery  of  Lycopodium  Selago,  associated  with  Azor- 
ella  Selago,  a  very  similar  plant  in  external  appearance.  In 
addition  to  the  foregoing  there  are  three  colonised  vascular 
plants,  namely,  Stellaria  media,  Cerastium  triviale  and  Poa 
annua  ;  and  Mr.  Hamilton  states  that  he  also  collected 
Tillcea  muscosa  and  two  sedges,  but  the  specimens  were 
lost.  If  we  except  three  imperfectly  known  grasses,  which 
Mr.  Kirk  has  described  as  new  (24),  there  are  no  endemic 
plants  in  the  island.  The  vascular  cryptogams  are  all 
widely  spread,  two  of  them  recurring  in  the  northern  hemi- 
sphere. Of  the  flowering  plants  upwards  of  half  are  confined  to 
the  New  Zealand  region,  and  the  rest  have  a  wider  range. 
Stilbocarpa  polaris  ( Aral iacese)  and  Pleurophyllum  Hookerii 
(Composite)  are  the  two  most  remarkable  and  most  con- 
spicuous plants  in  this  meagre  flora ;  the  former  having 
large  rhubarb-like  leaves,  and  the  latter  silky,  silvery  leaves 
and  handsome  purple  flower-heads  in  long  racemes.  Colo- 
banthus,  Azorella,  Acczna  and  Uncinia  are  equally  charac- 
teristic in  the  South  American  region. 

Quite  recently  a  fresh  account  of  Lord  Howe,  Pit- 
cairn  and  Norfolk  Islands  has  appeared  (25),  but  it  con- 
tains nothing  new  on  the  botany  of  these  islands.  Special 
stress  is  laid  on  the  beauty  of  the  vegetation  of  Howe 
Island,  where  palms  and  tree  ferns  abound,  and  fig-trees  of 
the  banyan  type  attain  dimensions  hardly  exceeded  else- 
where. What  is  known,  however,  of  the  botany  of  this 
interesting  island  has  appeared  in  Government  Reports  and 
scattered  in  a  variety  of  publications  (26-29)  of  limited 
circulation.  It  is  true  that  Sir  F.  von  Mueller  long  ago 
published  (30)  a  bare  list  of  all  the  plants  known  to  him 
from  the  island,  but  it  is  incomplete,  and  supplies  no  in- 
formation beyond  the  names  of  the  plants.  This  being  so, 
I  am  preparing  a  detailed  account  of  the  flora  of  this  island 
with   a  view  to   publication  elsewhere.      I   may  here  give, 


INSULAR  FLORAS.  297 

however,  some  particulars  gleaned  from  the  publications 
referred  to,  though  they  are  mostly  anterior  to  the  date 
(1885)  to  which  I  have  limited  myself  generally  in  these 
articles,  adding  a  few  remarks  of  my  own  on  the  distribu- 
tion of  the  plants. 

Lord  Howe  Island  is  of  small  extent  and  peculiar  con- 
formation, situated  about  300  miles  from  the  coast  of 
New  South  Wales  in  310  35'  S.  lat.  It  is  seven  miles 
long  with  an  average  breadth  of  one  mile,  and  the  steep 
circular  flat-topped  elevations  rise  to  a  height  of  nearly 
3000  feet.  Norfolk  Island,  the  nearest  land  to  the  north- 
east, is  about  500  miles  distant,  and  New  Zealand,  to  the 
south-east,  somewhat  farther  off.  The  island  is  of  volcanic 
origin,  consisting  of  three  basaltic  masses  connected  by 
coral-sand  rock.  About  165  species  of  indigenous  flower- 
ing plants  are  known,  and  forty-eight  ferns  and  lycopods. 
As  already  indicated  palms  form  a  conspicuous  feature  in 
the  scenery.  There  are  four  species,  all  endemic,  and 
they  have  been  very  much  named,  though  three  out  of 
the  four  are  well  known  under  the  generic  name  of  Kentia. 
They  are  K.  Belmoreana,  K.  Canterburyana  and  K.  For- 
steriana — names  familiar  to  many  persons,  as  they  have 
long  been  favourite  palms  in  cultivation  on  account  of  their 
elegance  and  hardiness.  A  tall  and  graceful  specimen  of 
K.  Forsteriana  is  one  of  the  finest  ornaments  of  the  central 
part  of  the  palm-house  at  Kew.  The  fact  of  there  being 
a  good  market  for  the  seeds  of  these  insular  palms  has  led 
to  considerable  destruction  of  the  trees  to  obtain  them  ;  but 
I  believe  the  Government  of  New  South  Wales  has  made 
it  a  punishable  offence  to  destroy  trees  on  public  territory. 
Beccari  (31)  has  founded  the  genus  Howea  for  them,  which, 
if  accepted,  is  the  only  endemic  one.  There  are  also  four 
indigenous  tree  ferns,  three  of  which  are  endemic.  But  the 
banyan  trees  {Fiats  columnaris)  are  perhaps  the  most 
striking  objects  in  the  vegetation.  Several  appear  in  the 
photographs  illustrating  Wilson's  Report,  one  of  which  is 
said  to  cover  an  area  of  three  acres  !  Morcea  Robinsoniana 
is   an   outlying  gigantic  member   of  an   African  genus    of 

Irideae  very  closely  allied  to  Iris  itself.      It  is  known  as  the 

21 


298  SCIENCE  PROGRESS. 

wedding-flower,  and  there  is  a  fine  specimen  of  it  at  the 
south  end  of  the  cactus-house  at  Kew.  Carmichcelia  exul 
(Leguminosae)  is  the  only  species  of  a  considerable  genus, 
with  this  exception,  not  known  to  inhabit  any  other  country 
than  New  Zealand.  There  are  other  connections  with  the 
flora  of  the  latter  country,  but  they  are  mostly  such  as  extend 
to  Australia  as  well.  Pimelea  longifolia  and  the  handsome 
sedge,  Gahnia  xantkocarpa,  are  apparently  exceptions.  In 
round  numbers  25  per  cent,  of  the  species  of  flowering  plants 
of  Lord  Howe  Island  are  endemic,  and  62  per  cent,  are 
common  to  Australia,  many  of  these  having  a  wider 
range.  A  few  are  common  only  to  Australia,  New  Zealand, 
and  Norfolk  Island.  The  shrubby  violaceous  genus 
Hymenanthera  is  an  example.  The  gum  trees  {Eucalyptus) 
of  Australia  are  represented  by  the  endemic  Acicalyptus 
Fullagari,  a  small  Fijian  genus  differing  from  Eucalyptus 'in 
having  a  calyptrate  calyx-limb  and  separate  petals.  Two 
other  conspicuous  trees  in  the  endemic  element  are  Draco- 
phyllum  Fitzgeraldii  (Epacridese)  and  the  screw-pine,  Pan- 
danus  Forsteri.  The  former  is  a  tree,  said  to  be  the  largest 
in  the  order,  attaining  the  height  of  fifty  to  sixty  feet.  It  has 
the  foliage  and  aspect  of  a  monocotyledon  rather  than  of  a 
dicotyledon.  One  characteristic  Australasian  type  we  miss 
in  the  Lord  Howe  Island  flora,  and  that  is  Cor dy line. 

When  reviewing  (32)  the  newer  literature  relating  to 
the  flora  of  the  Galapagos  Islands  I  found  little  to  add  to 
what  had  been  done  by  Darwin,  Hooker  and  Andersson  ; 
merely  mentioning  the  visit  of  the  United  States  ship 
Albatross,  and  Dr.  G.  Baur's  theory  of  the  origin  of  the 
fauna  and  flora.  Since  then  an  account  of  Dr.  Baur's 
botanical  collections  has  been  published  (33),  and  the  sub- 
stance has  also  appeared  in  an  English  journal  (34),  and 
Dr.  Baur  himself  has  written  (35)  and  lectured  (36)  in 
defence  of  his  theory  of  the  origin  of  this  group  of  islands. 
As  previously  stated,  he  contends  that  the  evidence  points 
to  the  present  condition  being  the  result  of  subsidence  ; 
that  the  islands  were  formerly  connected  with  each  other 
and  at  a  still  earlier  period  with  continental  America. 
Although  this  theory  has  been  derided,  I  think  the  biologi- 


INSULAR  FLORAS.  299 

cal  data  strongly  favour  its  correctness,  and  the  soundings 
given  in  the  map  accompanying  Agassiz's  report  (2,7)  of 
the  Albatross  expedition  show  a  relatively  shallow  area 
in  which  the  Galapagos  Islands  are  situated,  and  which 
extends  eastward  to  the  mainland  of  Veraguas.  Probably 
the  separation  would  be  greatly  anterior  to  the  segregation 
of  the  West  Indian  Islands. 

In  the  Botany  of  the  Challenger  expedition  (38)  I 
attempted  a  rough  classification  of  islands  in  relation  to  the 
composition  of  their  floras.  These  are  defined  as  follows  : 
1,  Vegetation  comprising  a  large  endemic  element  including 
distinct  generic  types  ;  2,  vegetation  comprising  a  small, 
chiefly  endemic  element,  the  derivation  of  which  is  easily 
traced  ;  and  3,  vegetation  containing  no  endemic  element. 
Without  due  consideration  the  Galapagos  were  referred  to 
the  first  category.  Sir  Joseph  Hooker  (39)  fully  realised 
the  absolute  American  affinities  of  the  flora  ;  but  he  analysed 
and  discussed  it  as  a  derived  one  rather  than  as  a  remnant. 
Darwin,  through  some  misinterpretation  of  the  statistics  sup- 
plied to  him,  fell  into  a  singular  error  respecting  the  generic 
endemic  element  in  the  Galapagos  (40).  Referring  to 
the  Compositse,  he  says  :  "  There  are  twenty-one  species, 
of  which  twenty  are  peculiar  to  this  archipelago  ;  these 
belong  to  twelve  genera,  and  of  these  genera  no  less  than 
ten  are  confined  to  the  archipelago  !  "  How  this  error  arose 
it  is  impossible  to  say,  but  as  a  matter  of  fact  the  statement 
quoted  is  wrong  (and  was  wrong  at  the  time  it  was  written) 
in  all  its  details.  With  regard  to  assumed  endemic  genera 
of  Compositae,  five  were  founded  on  galapageian  plants, 
namely,  Microcoecia  and  Desmocephalum,  since  reduced  to 
Elvira  ;  Macrcea  to  Lipochczta  ;  and  Scalesia  and  Lecocar- 
pus  are  so  near  to  Mirasolia  and  Melampodinm  respectively 
that  the  late  Mr.  Bentham  gave  it  as  his  opinion  that  they 
might  well  be  reduced.  Two  genera  from  these  islands 
belonging  to  other  orders  have  also  been  reduced.  These 
are  Galapogoa  =  Coldtnia  (Boraginacae),  and  Dictyocalyx 
=  Cacabus  (Solanacese) ;  and  Pleuropetalum  (Amarantaceas) 
has  since  been  found  in  several  localities  in  Western 
America.     Taking  this  view  of  their  affinities,  there  is  not 


3oo  SCIENCE  PROGRESS. 

a  single  genus  of  flowering  plants  endemic  in  the  Galapagos  ; 
but  each  island  has  its   distinct  species.      Briefly  put  then, 
the  genera  are  the  same  in  all  the  islands,  and  the  genera 
are  American  ;  whereas  a  large  proportion  of  the   species 
are  peculiar   to   each   island,   though    they   are  not  so  ex- 
clusively confined   to   single   islands   as    Darwin   supposed. 
On  this  point  he  says  (41)  :  "  Again  Euphorbia,  a  mundane 
or  widely  distributed  genus,  has  here  eight  species  of  which 
seven  are  confined  to  the  archipelago,  and  not  one  found  on 
any  two   islands.     Acalypha   and   Borreria,   both  mundane 
genera,  have  respectively  six  and  seven  species,  neither  of 
which  genera  has  the  same  species  on  two  islands,  except 
in  the  case    of    one    species    of    Borreria."       Dr.    Baur's 
recent  explorations  necessitate  a  considerable  modification 
of  this  statement ;  yet  in  a  sense  they  confirm  and  empha- 
sise it.      Baur  himself  deals  more  particularly  with  the  fauna 
(36)  in  illustration  of  this   phenomenon.      More   than   400 
specimens  of  the  lizard  genus    Tropidurus  were   collected, 
and  in  the  result  he  found  that  "each  island  possessed  only 
a  single  species  ;  all  the   individuals  of  an  island  belonged 
to  one  species  ;    and   nearly  every  island   had  its   peculiar 
species  or  race  ". 

The  botanists  who  worked  out  Dr.  Baur's  collections 
selected  Euphorbia  viminea  (33)  as  an  example  of  a  plant 
exhibiting  racial  differences  in  each  of  the  eight  islands, 
where  it  is  now  known  to  occur.  The  genera  Acalypha 
and  Borreria  are  cited  as  other  instances.  On  the  other 
hand,  Euphorbia  articulata,  which  was  collected  on  four 
different  islands,  showed  no  such  tendency. 

In  a  former  article  in  this  journal  (32)  I  mentioned  the 
fact  that  huge  branching  Cactacese  form  one  of  the  most 
striking  features  in  the  lower  zone  of  the  vegetation  of  the 
Galapagos,  and  I  have  elsewhere  (42)  given  some  par- 
ticulars of  what  is  known,  and  how  little  is  known  of  these 
Cactaceae  ;  and  I  may  repeat  here  that  specimens  of  only 
one  species  have,  so  far  as  I  can  ascertain,  been  brought 
away  from  the  islands.  These  were  brought  to  this  country 
by  Darwin,  and  published  by  Henslow  (43)  under  the 
name  of  Opuntia  galapageia.     This  species  is  remarkable 


INSULAR  FLORAS.  301 

in  the  genus  for  its  very  small  flowers,  which  are  only  about 
three-quarters  of  an  inch  in  diameter,  and  also  for  the  small 
number  of  petals  ;  but  as  the  figure  was  made  from  dried 
specimens,  it  may  be  inaccurate  in  some  details.  In  the 
same  place  it  is  mentioned  that  a  species  of  Cereus  was 
common  in  the  island,  but  was  not  found  in  flower. 

Darwin  himself  specially  alludes  (44)  to  the  prominent 
feature  these  Cactacese  are  in  the  landscape,  and  likewise 
to  the  fact  that  they  grow  in  the  rough  lava  where  there  is 
absolutely  no  other  phanerogamic  vegetation.  He  further 
points  out  their  importance  as  food  for  the  gigantic  tor- 
toises and  land  lizards.  They  are  also  a  source  of  water 
during  the  severe  droughts,  which  often  parch  the  lower 
zone. 

Subsequent  travellers  have  dwelt  upon  the  part  the 
Cactacese  play  in  the  biology  of  the  island,  and  Andersson, 
a  botanist  who  visited  the  islands  in  1852,  states  (45)  that 
he  observed  four  or  five  species,  but  had  time  neither  to 
prepare  specimens  nor  sketch  the  plants. 

My  note  on  the  subject  in  Nature  came  under  Dr. 
Baur's  notice,  and  he  forwarded  me  two  photographs,  one  re- 
presenting a  fine  example  of  an  arboreous  Opuntia  of  great 
size,  and  the  other  a  view  embracing  a  number  of  large 
Cerei,  together  with  a  transcript  of  his  notes  on  the  subject 
in  a  paper  (46)  which  I  had  not  seen.  He  was  struck  by 
the  difference  in  the  appearance  of  the  Optmtice  on  the 
different  islands,  and  observed  that  the  large  Opuntia  has 
a  different  habit  on  nearly  every  island.  Thus,  on  Barring- 
ton,  Indefatigable  and  South  Albemarle,  it  develops  a 
very  tall  stem  ;  on  Charles  and  Hood  a  relatively  short 
but  thicker  stem  ;  on  Jervis  a  very  short  stem,  branch- 
ing from  very  near  the  ground,  and  on  Tower  Island 
it  forms  no  stem  at  all,  and  appears  as  a  dwarf  bush. 
Dr.  Baur  attributes  these  modifications  to  the  varying  degrees 
of  humidity,  the  greatest  development  occurring  in  the  driest 
climate.  In  the  lower  region  of  South  Albemarle,  up  to 
about  500  feet,  the  Opuntia  is  very  common,  attaining  a 
large  size,  the  largest  being  about  twenty  feet  high,  with  a 
trunk  two  feet   in  diameter.     "  In  old  trees  the  bark  looks 


302  SCIENCE  PROGRESS. 

very  much  like  that   of  a  pine,    and  peels  off  in  very  thin 
sheets." 

The  common  Cereus,  which  strongly  resembles  C. 
peruvianus,  attains  almost  the  same  dimensions  ;  but  this 
is  all  we  know  about  it  at  present,  and  there  is  clearly 
much  more  botanical  work  to  be  done  in  the  Galapagos 
before  the  subject  is  exhausted.  It  may  be  of  interest  to 
add  that  no  species  of  cactus  inhabits  the  island  of  Juan 
Fernandez,  but  this  may  be  ascribed  to  climatic  differences. 
Indeed,  so  far  as  is  known,  none  of  the  other  Pacific  American 
islands,  at  any  considerable  distance  from  the  coast,  support 
any  members  of  the  order,  though  Malpelo,  for  example, 
is  barren  enough  to  give  them  a  chance  of  flourishing. 

Another  remarkable  element  in  the  flora  of  the  Galapagos 
is  the  relatively  large  number  of  species  of  the  small  order 
Amarantacese.  About  fifteen  species  are  now  known  to  in- 
habit the  islands,  and  twelve  of  them  are  endemic.  They 
belong  mainly  to  the  genera  Telautkera,  Alternanthera, 
and  Froelichia. 

Concerning  the  flora  of  the  Arctic  Islands  in  relation  to  the 
adjacent  continents,  I  have  to  add  a  few  references  (47-48) 
to  works  of  older  date  than  my  paper  (49),  and  a  few  recent 
ones  of  unusual  interest.  Mr.  Trevor- Battye's  account  of 
the  vegetation  of  Kolguev  Island  (50)  and  Colonel  Feilden's 
contributions  on  the  subject  (51-52)  rank  first  among  these. 
The  former  noted  ninety-five  species  of  phanerogamia  in 
Kolguev,  and  his  observations  on  the  vegetation  are  of 
great  value.  About  a  score  of  the  plants  recorded  by 
Ruprecht  (53)  were  not  found,  and  Trevor-Battye  remarks 
on  the  absence  of  Saxifraga  oppositifolia,  Mertensia  maritima 
and  Ledum  palustre.  Colonel  Feilden's  short  paper  on 
Spitsbergen  plants,  as  well  as  his  remarks  on  mild  arctic 
climates,  is  worthy  of  attention  on  account  of  his  experience. 
The  only  information  I  have  found  (54)  respecting  the 
vegetation  of  Einsamkeit  Island  is  that  there  is  no  grass 
carpet,  and  it  is  added  that  there  is  a  great  quantity  of  drift- 
wood, sometimes  far  inland.  A  new  list  (55)  of  Iceland 
and  Faeroe  plants  does  not  claim  to  be  anything  more  than 
a  contribution  to  local  distribution. 


INSULAR  FLORAS.  303 

There  is  little  new  literature  relating  to  the  Atlantic 
Islands,  but  Sir  Joseph  Hooker's  comparison  (56) 
of  the  Maroccan  and  Canarian  floras  was  overlooked  by  me 
when  reviewing  the  writings  of  Dr.  Christ.  In  an  article 
(57)  of  more  recent  publication,  the  latter  gives  expression 
to  a  considerable  modification  of  his  views  on  the  affinities 
of  the  Canarian  flora.  He  now  recognises  a  much  more 
intimate  connection  with  the  old  African  flora.  But  I  must 
not  reopen  the  subject  here. 

One  important  contribution  (58)  to  the  flora  of  the  West 
Indies  has  appeared.  This  part  consists  of  a  critical 
elaboration  of  the  Myrtaceae,  than  which  there  was  probably 
no  group  of  plants  more  in  need  of  revision.  It  is  some- 
what appalling  to  see  such  familiar  trees  as  the  allspice  and 
clove  with  a  page  and  half  of  synonyms  each  ;  yet  it  is 
very  useful,  historically,  as  well  as  for  practical  purposes,  to 
have  them  brought  together. 

W.     BOTTING    HEMSLEY. 

(To  be  continued.} 


THE  PRESENT  POSITION  OF  THE  CELL- 
THEORY. 

(CONCLUSION.) 

THUS  far  I  have  tried  to  rehabilitate  the  cell  as  a  vital 
unit.  I  have  now  to  deal  with  the  further  question  as 
to  the  part  played  by  the  cell  in  the  composition  of  the  higher 
animals  and  plants.  In  the  earlier  part  of  this  essay  I 
stated  that  Mr.  Adam  Sedgwick  denied  in  toto  the  proposi- 
tion that  "the  elementary  parts  of  all  tissues  are  composed 
of  cells  ".  Since  writing  those  words,  Mr.  Sedgwick's  reply 
to  my  previously  published  criticisms  has  appeared,1  and  I 
find  that  I  have  made  a  mistake.  For  he  does  not  deny 
the  proposition,  but  says:  ''The  assertion  that  organisms 
present  a  constitution  which  may  be  described  as  cellular  is 
not  a  theory  at  all  ;  it  is — having  first  agreed  as  to  the 
meaning  and  use  of  the  word  cell — a  statement  of  fact  and 
no  more  a  theory  than  is  the  assertion  that  sunlight  is  com- 
posed of  all  the  colours  of  the  spectrum  ".  I  can  only  beg 
Mr.  Sedgwick's  pardon.  I  certainly  was  led  to  suppose 
from  his  earlier  writings  that  he  regards  the  cell  as  a 
nonentity,  in  so  far  as  it  may  be  considered  to  be  the 
ultimate  structural  unit  of  the  metazoa,  and  I  recoiled  from 
his  suggestion  that  the  essence  of  development  lay  in  "a  multi- 
plication of  nuclei  and  a  specialisation  of  tracts  and  vacuoles 
in  a  continuous  mass  of  vacuolated  protoplasm  ". 

Mr.  Sedgwick  now  explains  that  he  objects,  not  to  the 
statement  that  tissues  are  composed  of  cells — or,  in  his  own 
words,  that  they  have  a  composition  which  may  be  described 
as  cellular — but  to  the  statement  that  an  individual  meta- 
zoon  is  an  aggregate  of  lesser  individuals,  or,  as  it  has  often 
been  expressed,  a  cell  colony  or  cell  republic.  I  have  else- 
where— and  as  Mr.  Sedgwick  well  says,  after  great  effort — 
come  to  agree  with  him  on  this  point,  for  a  careful  survey 
of  a  considerable  range  of  facts  led  me  to  the  conviction 

1  Adam  Sedgwick,  "Further  Remarks  on  the  Cell-Theory,  with  a  Reply 
to  Mr.  Bourne,"  Quart,  four.  Micr.  Sci.,  vol.  xxxviii.,  p.  331,  1895. 


THE  PRESENT  POSITION  OF  CELL-THEORY.     305 

that  the  idea  of  a  cell  republic  was  inappropriate.  Such 
being  the  case  I  would  willingly  have  buried  the  hatchet, 
but  when  I  had  already  dug  the  hole  to  bury  it  in,  my  hand 
was  stayed  by  some  criticisms  on  his  views  and  on  mine 
which  have  just  been  published  in  a  contemporary  periodi- 
cal.1 These  criticisms  have  restored  to  me  the  conviction 
which  I  held  when  I  ventured  to  write  a  criticism  of  Mr. 
Sedgwick's  views  ;  a  conviction  that,  as  he  originally 
expressed  them,  they  were  calculated  to  mislead  and  to  do 
harm  to  the  very  cause  whose  interests  he  was  desirous  to 
promote.  As  he  has  lately  explained  that  he  did  not  mean 
what  I  supposed  him  to  mean,  there  is  no  need  for  quarrel- 
ling any  further  with  him,  but  he  will  himself  allow  that  I 
was  amply  justified  when  I  gave  the  following  as  a  not 
unfair  statement  of  his  position.  That  from  the  connection 
known  to  exist  between  some  cells  composing  adult  tissues, 
there  is  an  antecedent  probability  that  similar  connections 
exist  between  all  cells  composing  all  tissues ;  and  this 
probability  is  heightened  by  observations  made  on  the 
development  of  Peripatus,  by  the  fact  that  the  so-called 
mesenchyme  cells  in  Avian  and  Selachian  embryoes  are 
continuous  and  not  isolated  as  was  once  supposed,  and  by 
a  study  of  the  developing  nerves  of  Elasmobranchs.  And 
that  it  follows  from  this  that  the  morphological  concept  of  a 
cell  so  far  from  being  of  primary  is  altogether  of  secondary 
importance,  and  that  progress  in  the  knowledge  of  structure 
is  impossible  so  long  as  men  persistently  regard  cells  as  the 
fundamental  structural  units  on  which  the  phenomena  mani- 
fested by  organised  beings  depend.  The  true  method  of 
inquiry  must  be  a  study  of  the  growth,  extension,  vacuolation 
and  specialisation  of  the  living  substance  protoplasm. 

He  has  been  understood  by  others  as  I  understood  him, 
and  indeed  he  had  so  expressed  himself  that  he  could 
scarcely  have  been  understood  otherwise.  What  I  had 
anticipated  has  happened.  Persons,  ready  to  grasp  at 
novel  ideas,  have  said  in  their  hearts  :  "Tush,  there  is  no  cell ! 
There  are  protoplasmic  masses  which  may  contain  one  or 
many  nuclei  ;  the  mass   is  of  no  importance,  it   is  scarcely 

x  Natural  Science,  vol.  vii.,  No.  46,  December,  1S95. 


306  SCIENCE  PROGRESS. 

more  than  the  medium  in  which  the  nucleus  lives,  and 
through  which  it  exhibits  its  powers.  The  nucleus  may 
move  about  in  the  mass,  acquiring  '  spheres  of  influence ' 
at  its  halting  places,  and  so  producing  the  vital  phenomena. 
It  is  the  nucleus  which  is  the  vital  unit,  and  there  is  no 
bond  between  nucleus  and  cytoplasm  which  shall  compel 
us  to  regard  their  union  as  the  necessary  condition  of  living 
individuality." 

I  have  made  use  of  my  own  expressions,  but  if  this  is  not 
the  plain  meaning  of  the  short  editorial  entitled  "The 
Reign  of  the  Nucleus"  in  the  January  number  of  Natural 
Science,  what  is  ? 

The  writer  of  the  editorial  is  so  captivated  with  the  pros- 
pect opened  up  by  his  interpretation — a  perfectly  legitimate 
interpretation — of  Mr.  Sedgwick's  writings,  that  he  forthwith 
abolishes  the  existence  of  cells  altogether  and  talks  glibly 
of  "  protoplasmic  masses,"  ignoring  the  fact  that  the  masses 
in  question  are  divided  up  into  corpuscles.  Following  up 
his  theme  of  protoplasmic  masses  dominated  by  nuclei,  he 
lightly  dismisses  the  arguments  which  I  put  forward, 
saying  that  the  segmentations  of  Nereis,  Unio,  etc.,  exhibit 
nuclear  lineage  rather  than  cell  lineage  (who  could 
hold  such  an  opinion  after  a  careful  study  of  Wilson  and 
Lillie's  figures  ?),  and  winds  up  with  the  following  astonish- 
ing piece  of  criticism  :  "  In  drawing  an  argument  for  the 
cell-theory  from  the  definite  places  assigned  to  cells  in 
development  Bourne  seems  to  us  to  have  overlooked  the 
experiments  of  Wilson,  Driesch  and  Hertwig,  who  have 
shown  that  the  nuclei  may  be  moved  about  in  the  proto- 
plasmic mass  almost  as  freely  as  a  '  heap  of  billiard  balls 
may  roll  over  each  other ' ".  I  rubbed  my  eyes  and 
wondered.  I  thought  I  knew  the  works  of  Driesch, 
Hertwig  and  Wilson  pretty  well,  and  that  I  had  considered 
them  carefully,  and  I  had  certainly  regarded  them  as  strong 
evidence  in  favour  of  the  cell-theory  as  I  conceived  of  it. 
A  short  search  soon  hit  upon  the  passages  which  are 
professedly  quoted.      First  for  Driesch  : x  "  Die  Furchungs- 

1  Hans  Driesch,  Entwicklungmechanischse  Studien,  iv.,  Zeitschrift  fUr 
IViss.  Zoologie,  vol.  Iv.,  1893. 


THE  PRESENT  POSITION  OF  CELL-THEORY.     307 

kugeln  der  Echiniden  als  ein  gleichartiges  Material 
anzusehen  sind,  welches  Man  in  beliebiger  Weise,  wie 
einen  Haufen  Kugeln  durch  einander  werfen  kann,  ohne 
dass  seine  normale  Entwicklungsfahigkeit  darunter  im 
Mindesten  leidet  ".  (The  segmentation  spheres  of  Echinids 
are  to  be  regarded  as  a  homogeneous  material  which  one  may 
roll  amongst  one  another  at  will  like  a  heap  of  balls,  without 
thereby  destroying  in  the  least  their  capacity  for  develop- 
ment.) No  hint  whatever  of  rolling  the  nuclei  through  the 
protoplasmic  mass.  The  statement  is  made  of  Furchungs- 
kugeln,  that  is  of  cells,  and  it  is  the  cells  that  one  may  roll 
about  like  balls.  Not  a  bad  argument  for  my  contention, 
that  the  blastomeres  of  many  developing  ova  are  disjunct. 
If  there  were  any  doubt  as  to  Driesch's  words  a  study  of 
figures  39-68  which  illustrate  his  paper  would  satisfy  the 
most  exacting.  The  blastomeres  are  unusually  distinct 
from  one  another,  especially  in  the  embryoes  illustrated  by 
figs.  63  and  67.  Now  for  Hertwig:1  "Bei  den  verschiedenen 
Modificationen  des  Furchungsplasma  werden  die  aus  dem 
ersten  Furchungskern  durch  aufeinanderfolgendeTheilungen 
erzeugten  Kerngenerationen  Theilen  des  Dotters,  die  in  Eir- 
aum  eine  sehr  verschiedene  Lage  einnehmen,  zuoetheilt  und 
mit  ihnem  zu  einem  zellkorper  verbunden.  Die  Kerne  wer- 
den in  Eiraum  wie  ein  Haufen  von  Kugeln  durch  einander 
gewurfelt."  This  is  a  very  complicated  German  sentence 
and  might  well  lead  to  a  misunderstanding,  but  it  comes  out 
all  right  in  plain  English.  "In  the  various  modifications  of 
the  divisional  processes  the  nuclear  generations,  which  are 
produced  by  successive  divisions  from  the  segmentation 
nucleus,  are  assigned  to  a  portion  of  the  yolk  which  occupies 
very  different  positions  within  the  limits  of  the  egg,  and  are 
bound  with  it  to  form  a  cell  body.  The  nuclei  are  rolled 
one  over  another  within  the  limits  of  the  egg  like  a  heap  of 
balls."  This  passage  is  a  summary  of  preceding  state- 
ments and  inferences,  and  it  might  be  held  to  bear  a  very 
different  meaning  to  that  which  it  does  bear  ;  the  illustration 

1  O.  Hertwig,  "  Ueber  den  Werth  der  ersten  Furchungszellen  fur  die 
Organbildung  der  Embryo,"  Arch,  fur  Mikr.  A  nat.,  vol.  xlii.,  p.  662,  1893. 


308  SCIENCE  PROGRESS. 

of  the  heap  of  balls  is  a  very  loose  one.  To  understand 
the  meaning  of  the  summary  one  must  turn  to  pp.  678-685 
of  the  same  memoir,  which  consist  of  a  section  entitled 
"  Erklarung  des  abnormen  Furchungsverlaufes  ".  There 
we  learn,  as  we  had  previously  learnt  from  Driesch,  that 
the  divisional  planes  of  segmenting  ova  are  determined  by 
the  direction  of  the  nuclear  spindles  and  that  the  orientation 
of  the  first  nuclear  spindle  is  determined  by  the  character  of 
the  body  of  the  ovum  and  its  contents.  The  ova  of  Echinus 
are  homogeneous  throughout,  and  orientation  of  the  first 
nuclear  spindle  is  a  chance  affair.  But  the  ovum  of  the 
Frog  is  not  homogeneous  ;  it  consists  of  a  smaller  cap  of 
protoplasm  resting  on  a  large  body  of  yolk,  and  the  nucleus 
lying  in  the  cap  of  protoplasm,  the  direction  of  the  first 
nuclear  spindle  is  determined  by  its  relations  to  the  more 
active  yolk  on  the  one  hand,  and  the  denser  food  yolk  on 
the  other.  The  relations  of  the  food  yolk  and  protoplasm 
are  changed  by  the  pressure  applied  during  the  experiments 
and  the  changes  are  different  according  as  the  pressure  is 
applied  vertically  or  horizontally.  Hence  the  direction  of 
the  first  and  the  succeeding  nuclear  spindles  is  changed 
in  different  senses,  according  to  the  pressure  employed.  As 
the  divisional  planes  are  always  at  right  angles  to  the 
nuclear  spindles,  the  positions  of  the  two  first  and  the  suc- 
ceeding blastomeres  differ  according  as  the  pressure  applied 
is  vertical,  horizontal,  oblique,  or  circumferential.  One  may 
in  fact  cause  the  blastomeres  and  their  contained  nuclei  to 
take  up  what  position  one  will  by  varying  the  direction  of 
the  pressure.  In  this  sense,  and  in  this  sense  only,  can  one 
speak  of  rolling  the  nuclei  about  like  balls.  Not  a  word  about 
a  protoplasmic  mass  through  which  the  nuclei  are  caused  to 
roll.  On  the  contrary,  a  great  deal  about  planes  of  division 
and  splitting  up  of  the  egg  into  corpuscles  round  the  nuclei. 
It  only  requires  a  glance  at  Hertwig's  figures  and  diagrams 
to  show  that  the  blastomeres  are  as  distinct  during  abnor- 
mal division  as  during  normal  division,  and  that  there  is  not 
at  any  time  any  question  of  a  "protoplasmic  mass,"  a  cir- 
cumstance which  has  been  well  understood  by  everybody 
who  has  taken  the  trouble  to  read  his  memoir  carefully. 


THE  PRESENT  POSITION  OF  CELL-THEORY.      309 

Most  of  the  experiments  of  Wilson,  Hertwig  and 
Driesch  were  of  a  different  kind.  They  isolated  the  blas- 
tomeres  by  gentle  shaking.  Driesch  is  very  careful  to  say 
gentle  ;  rough  shaking  destroyed  the  individual  blastomeres. 
Things  which  are  so  loosely  united  as  to  be  separated  thus 
easily  from  one  another  scarcely  suggest  the  nature  of  a 
coherent  protoplasmic  mass. 

The  criticism  falls   entirely  to  the  ground  and  one  can 
only  wonder  how  any  one  could  have  had   the  temerity  to 
make  it.      The  very  objections  urged  to  my  views  are  but 
additional   evidence  in   support  of  them,    and   I    was   well 
aware  that  the  evidence  existed  when  I  wrote,  but  I  had  to 
be  as  brief  as  possible,  and  did  not  refer  to  it.      My  state- 
ment   that    it    is   very    clearly    established    that    there    are 
numerous   cases  in  which  there    is  not   "a  primitive   con- 
tinuity   which     has     never    been     broken"    is    abundantly 
justified.      Mr.    Sedgwick  wonders   why    I   emphasised  the 
distinction  and  complete   isolation  of  the  cells  formed  by 
the  segmentation   of  the   egg.     The  reason   is  surely  clear 
enough.      Because  he  suggested,  in  no  uncertain  manner  in 
his  earlier  writings,  that  the  connections  between  adult  cells 
were  due  to  a  primitive  continuity  which  had  never  been 
broken,   and  that  those  who  urged  that  such  connections 
were  secondary  were   in  the  wrong.     This  suggestion  was 
contrary  to  fact,  and  it  was  my  object  to  show  that  it  was. 
I    did   not    contradict    myself  when    I    stated    immediately 
afterwards  that  the  organism  cannot  be  considered  to  consist 
of  independent  life  units,   for    I  went  on   to  show  that  the 
cell-republic  theory  is  also  contrary  to  fact,  and  must  there- 
fore be  condemned.      If  a  contradiction  exists,  it  exists  in 
nature,   and   after  we  have   ascertained  the  facts  the  next 
thing  is  to  try  to  explain  this  seeming  contradiction.     Mr. 
Sedgwick  says  that  he  does  not  think  it  possible  to  do  so, 
until  we  acquire  some   more  understanding  of  the  relative 
functions  of  nuclei  and   protoplasm.      Possibly  he   is  right, 
yet  I  think  that  an  attempt  may  be  made,  and  if  the  explana- 
tion is  after  all  not  very  satisfactory  yet  some  service  may 
be   done,    for  we    may  arrive   at   more   distinct  ideas  about 
fundamental   points,  and  we  must   gain   much   by  a  careful 


310  SCIENCE  PROGRESS. 

classification  of  the  facts.  Such  a  classification  has  yet  to 
be  made.  So  long  as  a  theory  is  dominant,  as  the  cell- 
republic  theory  was,  exceptions  and  difficulties  are  glossed 
over,  or  are  explained  away  by  a  phrase.  When  I  made  a 
vigorous  onslaught  on  Mr.  Sedgwick,  I  was  afraid  that  he 
wished  to  substitute  King  Stork  for  King  Log  and  bring  us 
under  the  domination  of  a  new  theory  of  his  own.  His 
reply  to  my  strictures  and  his  careful  exposition  of  his  own 
standpoint  are  reassuring  on  this  point,  and  if  I  exceeded  the 
limits  of  courtesy  in  my  article,  I  did  so  under  a  misunder- 
standing and  express  my  regret  for  it.  Mr.  Sedgwick  has 
done  a  great  service  in  breaking  the  bonds  of  the  old  theory. 
Now  the  question  is,  having  got  our  liberty,  what  are  we 
going  to  do  with  it  ? 

Firstly,  I  think,  we  have  got  to  make  up  our  minds  as 
to  what  we  mean  by  a  vital  unit. 

In  the  first  part  of  this  essay  I  stated  that  the  cell  is  par 
excellence  the  vital  unit,  by  which  I  meant  nothing  more 
than  that  it  is  the  simplest  form  of  material  aggregate  in 
which  individual  life  is  possible.  There  would  seem  to  be 
no  objection  to  such  an  application  of  the  word  unit.  But 
the  term  unit  is  a  relative  one,  and  its  correlative  is 
multiple.  If,  therefore,  we  see  that  the  developing  embryoes 
of  many  animals  and  likewise  the  tissues  of  the  adult  forms 
are  made  up  of  structures  which  we  must  call  cells,  and  if 
we  call  the  cell  a  vital  unit,  we  are  obliged  to  conclude  that 
the  animals  in  question  are  composed  of  an  aggregate  of 
vital  units,  which  leads  us  directly  to  the  doctrine  of  a  cell- 
republic.  Thus  at  the  outset  we  are  confronted  by  the 
great  difficulty  that  what  experience  teaches  us  to  deny 
reason  compels  us  to  affirm. 

There  must  be  a  flaw  somewhere,  either  in  the  facts  or 
in  the  reasoning.  There  can  hardly  be  any  doubt  about 
the  facts  ;  the  flaw  therefore  must  be  in  the  reasoning,  and 
I  do  not  doubt  that  it  consists  in  our  insistence  on  applying 
the  idea  of  a  unit  to  biological  facts.  As  Whewell  would 
have  said,  the  idea  is  inappropriate.  The  term  unit,  as  we 
use  it  in  Biology,  conveys  a  double  meaning.  On  the  one 
hand,  it  borrows  part  of  its  meaning  from  the  idea  of  num- 


THE  PRESENT  POSITION  OF  CELL-THEORY.     311 

ber,  and  to  this  extent  the  term  is  used  in  an  equivalent 
sense  to  that  in  which  it  is  used  in  Physics.  But  put  side 
by  side  such  expressions  as  unit  of  mass  or  unit  of  time  with 
the  expression  unit  of  life,  and  a  little  reflection  will  suffice 
to  show  that  the  sense  is  inappropriate.  Nor  is  the  case 
made  better  if  we  compare  the  unit  of  life  with  the  chemical 
unit.  The  value  of  the  latter  consists  essentially  in  this, 
that  it  is  a  means  of  dealing  numerically  with  chemical  facts, 
and  experience  shows  that  ideas  of  number  are  very 
appropriate  to  chemical  facts.  With  life  the  case  is  very 
different.  In  the  present  state  of  our  knowledge  the  con- 
nection between  life  and  number  is  of  the  slenderest  kind, 
and  it  is  insufficient  to  justify  our  applying  numerical  ideas 
to  vital  phenomena. 

The  other  sense  in  which  the  term  unit  is  used  in 
Biology  is  purely  subjective.  It  stands  to  express  our  idea 
of  individuality,  an  idea  which  is  founded  on  our  own  states 
of  consciousness.  It  is  unnecessary  for  me  to  dilate  upon 
the  controversies  which  have  raged  round  this  idea  of  in- 
dividuality in  its  application  to  the  animal  kingdom.  The 
most  acute  reasoners  are  not  agreed  upon  the  precise 
point  where  individuality  ceases  to  belong  to  parts  and 
belongs  to  the  whole  even  in  some  of  the  simpler  colonial 
organisms,  and  in  such  cases  as  the  Siphonophora  a  satis- 
factory solution  of  the  problem  appears  to  be  hopeless. 

But  these  cases  are  simple  in  comparison  with  that 
which  we  are  now  discussing.  If  then  we  cannot  agree 
about  the  limit  of  individuality  in  colonial  organisms,  how 
are  we  likely  to  agree  about  the  same  thing  in  the  case  of 
organic  structure  in  general  ? 

There  is  this  to  be  said,  however,  that  for  us  the  test  of 
individuality  should  be  a  biological  test,  and  the  idea  is  there- 
fore more  appropriate  to  the  question  than  the  numerical  idea 
just  spoken  of.  It  was,  no  doubt,  the  recognition  of  its 
propriety  which  lent  such  force  to  Schwann's  argument, 
"  since  it  may  be  proved  that  some  cells,  which  do  not 
differ  from  the  rest  in  their  mode  of  growth,  are  developed 
independently,  we  must  ascribe  to  all  cells  an  independent 
vitality  ". 


3i2  SCIENCE  PROGRESS. 

Hence,  as  it  seems  to  me,  whilst  we  can  and  ought  to 
get  rid  of  the  numerical  idea  expressed  by  the  word  unit,  we 
cannot  get  altogether  rid  of  the  idea  of  individuality,  and 
we  must  do  our  best  to  bring  it  into  harmony  with  the  facts. 

Since  there  is  an  inseparable  connection  between  the 
idea  of  number  and  the  word  unit,  we  ought  to  get  rid  of 
the  expression  "  unit  of  life,"  and  use  some  other  term 
which  shall  denote  alike  the  simplest  and  the  most  com- 
plex of  living  beings.  The  word  organism  I  have  aheady 
objected  to  because  of  its  double  connotation — would  it  not 
be  better  to  make  use  of  such  a  word  as  "biont,"  which  is 
as  nearly  as  possible  the  equivalent  of  the  German  "  Leben- 
diges  "  ?  Anything  which  leads  or  is  capable  of  leading  an 
independent  individual  life  is  a  biont.  Thus  a  cell  may  be 
a  biont,  as  in  the  case  of  the  protozoa,  or  it  may  be  a  con- 
stituent part  of  a  biont,  as  in  the  case  of  the  metazoa.  In 
any  case  the  cell  is  the  simplest  form  of  biont  known,  for  if 
we  2"o  behind  the  cell  we  have  structures  which  are  not 
capable  of  leading  an  independent  individual  life. 

But  a  cell  in  the  case  of  metazoa,  or  the  nucleus  and 
other  structures  in  the  case  of  protozoa,  and  unicellular 
plants  are  things  which,  whilst  they  participate  in,  and  con- 
tribute to  life,  and  to  that  extent  may  be  considered  as  living, 
are  not  in  themselves  capable  of  independent  individual 
existence.     They  may  be  called  metabionts. 

The  terminology  suggested  may  not  be  perfect,  but  by 
the  use  of  it  or  of  something  equivalent  we  may  shake  our- 
selves free  of  the  false  ideas  which  have  clustered  about 
individual  life  units,  and  start  with  a  new  hope  on  an  inquiry 
into  the  nature  and  growth  of  bionts. 

An  essential  part  of  our  conception  of  a  biont  is  the 
union  of  two  substances,  cytoplasm  and  nuclein.  It  does 
not  matter,  for  present  purposes,  that  we  know  nothing 
exact  about  these  two  substances,  and  still  less  of  the 
manner  in  which  they  operate  together  to  produce  the 
phenomena  of  life.  It  suffices  that  we  know  that  there  are 
bionts  whose  structure  is  so  simple  that  we  can  affirm  no- 
thing more  of  them  than  that  they  consist  of  cytoplasm  and 
nuclein,  e.g.,  Bacteria,  Yeast,  Oscillaria,  etc. 


THE  PRESENT  POSITION  OF  CELL-THEORY.     313 

Within  the  limits  of  the  protozoa  we  study  many  kinds 
of  bionts  which,  whilst  retaining  great  simplicity  of  structure, 
have  advanced  far  beyond  the  stage  represented  by  these 
simple  forms. 

The  most  important  as  well  as  the  most  striking 
structural  advance  is  the  formation  of  a  nucleus.  The 
nuclein  which  was,  in  the  simplest  bionts,  distributed 
through  the  protoplasm,  is  aggregated  to  form  a  compact 
body,  which  from  its  structure  and  behaviour  may  be  re- 
garded as  a  metabiont,  as  also  may  the  part  from  which  it 
was  segregated,  the  cytoplasm.  The  steps  which  lead  up 
to  the  segregation  of  the  nucleus  are  obscure,  but  there  are 
very  good  grounds  for  saying  that  the  nucleus,  when  formed, 
is  connected,  in  some  manner  unknown  to  us,  with  the 
transmission  of  the  so-called  historic  qualities  of  the  biont. 
In  any  case  it  plays  a  leading  part  in  reproduction,  and  the 
steps  from  the  condition  of  diffused  nuclein  to  centralised 
nuclein  are  suggested  by  the  infusorian  Holosticha  scutelhim, 
which  ordinarily  has  no  definite  nucleus,  but  contains 
numerous  chromatin  particles  scattered  throughout  its  sub- 
stance. Previous  to  reproduction  by  division  the  scattered 
particles  are  drawn  together  and  unite  to  form  a  centralised 
nucleus,  which  divides  in  a  normal  manner  and  breaks  up 
again  into  particles  in  the  offspring.1 

Besides  the  nucleus  many  other  structural  advances  are 
to  be  noted  in  protozoa  and  in  unicellular  plants  ;  some 
must  be  regarded  as  metabionts,  e.g.,  chlorophyll  corpuscles 
and  chromatophores  of  various  kinds,  many  kinds  of  granules, 
etc.  Other  structures  cannot  be  regarded  as  belonging  to 
the  same  category,  e.g.,  cilia,  contractile  fibres,  etc.  We 
may  for  the  present  purpose  leave  both  cases  out  of  con- 
sideration, for  it  is  the  nucleus  and  the  part  it  plays  as  an 
essential  constituent  of  the  biont  which  most  concerns  us. 

We  have  as  yet  very  obscure  notions  about  the  co-opera- 
tion of  nucleus  and  cytoplasm  in  the  production  of  vital 
phenomena.  But,  putting  aside  the  views  of  those  who 
postulate  the  existence  of  minute  vital  units,  and  speak  of 

1  Aug.  Gruber,  "  Ueber  vielkernige  Protozoa,"  Biol.  Centralblatt,  iv.,  p. 
170.     See  also  the  same  author,  Zeit.fiir  Wiss.  Zool.,  xli.,  p.  186. 

22 


314  SCIENCE  PROGRESS. 

an  emanation  of  specialised  biophors  from  the  nucleus  into 
the  cytoplasm,  there  is  a  general  agreement  that  the  co- 
operation is  of  the  nature  of  a  complex  exchange  of 
chemical  material.  If  this  be  the  case,  the  rate  of  exchange 
must  be  the  measure  of  vital  activity,  and  it  is  clear  that 
the  rate  of  exchange  will  be  greatest  in  immediate  proximity 
to  the  nucleus  and  will  become  increasingly  less  the  greater 
the  distance  from  the  nucleus.  At  a  certain  distance,  which 
might  be  called  the  limit  of  nuclear  influence,  the  rate  of 
exchange  will  be  reduced  to  zero.  We  see  that  in  the 
protozoa  the  forms  which  have  a  single  nucleus  are  small, 
and  we  may  say,  in  consequence  of  the  foregoing-  considera- 
tions, that  their  size  is  determined  by  the  limits  of  nuclear 
influence.  But  many  protozoa  are  multinuclear,  and  I 
believe  that  there  is  no  exception  to  the  rule  that  protozoa 
of  relatively  large  size  are  also  multinuclear.  Such  is 
obviously  the  case  in  such  forms  as  Radiolaria,  Actino- 
sphserium,  Pelomyxa,  the  Myxomycetes  and  others.  From 
a  consideration  of  all  the  facts  of  the  case  we  may  legiti- 
mately infer  that  in  any  given  biont  growth  beyond 
certain  limits  is  incompatible  with  a  uninuclear  condition, 
and  that  further  growth  involves  multiplication  of  the 
nucleus,  which  may  have  as  consequences:  (i)  discon- 
tinuous growth,  which  in  its  simplest  form  is  reproduction 
by  binary  fission  :  (2)  continuous  growth,  in  which  the 
nucleus  is  multiplied  so  that  all  parts  of  the  enlarged  cyto- 
plasm may  receive  an  equal  share  of  nuclear  influence. 
There  are  numerous  cases  in  which,  as  I  pointed  out  before, 
the  two  conditions  are  combined.  There  is  a  ccenocytial r 
stage  of  considerable  duration,  followed  by  reproduction 
(or  discontinuous  growth). 

The  next  phase  is  the  formation  of  a  biont  of  consider- 
able size,  in  which  very  numerous  nuclei  are  arranged  in 
definite  manner  in  a  continuous  mass  of  protoplasm.  Such 
a  condition  is  represented  by  the  Cceloblastas,  and  also  in  the 

1  When  in  my  earlier  essay  I  coined  the  word  hypopolycytial  I  was 
not  aware  that  Professor  Vines  had  applied  the  term  ccenocytial  to  the 
Cceloblastse.  His  term  has  the  priority  and  is  more  euphonious,  so  I  adopt 
it  instead  of  my  own. 


THE  PRESENT  POSITION  OF  CELL-THEORY.     315 

growing  tissues  of  many  animals  and  plants,  as  for  instance 
in  the  embryoes  of  many  Arthropods,  in  the  endosperm  of 
Phanerogams,  etc.  The  condition  may  be  permanent,  as 
in  the  case  of  the  Cceloblastae,  or  non-permanent,  as  in  the 
other  cases.  But  in  both  instances  there  is  a  difference 
from  the  ccenocytial  condition  observed  in  Protozoa,  namely, 
that  the  multiplication  of  the  nucleus  does  not  lead  to  re- 
production in  the  form  of  the  splitting  up  of  the  biont  into 
as  many  new  bionts  as  there  are  nuclei. 

In  a  ccenocytial  biont  of  appreciable  size  the  relations 
of  the  various  parts  to  external  conditions  will  tend  to  be- 
come different,  and  differences  of  chemical  constitution  will 
be  set  up  in  the  different  regions  exposed  to  different  con- 
ditions. We  can  see  that  this  is  the  case  in  Botrydium,  in 
which  root  and  shoot  are  plainly  marked  off  from  one 
another,  and  better  still  in  Caulerpa,  in  Codium,  and  in 
many  of  the  Moulds.  Differences  in  chemical  constitution 
thus  induced  will  mean  difference  in  exchange  between 
nucleus  and  cytoplasm,  and  we  may  infer  that,  in  accordance 
with  these  differences,  the  cytoplasm  within  the  limit  of 
influence  of  any  one  nucleus  will  in  time  assume  a  con- 
stitution so  different  from  that  of  the  adjacent  cytoplasm  as 
to  become  sharply  marked  off  from  it.  It  will  then  acquire 
its  own  surface  tension — the  first  step  towards  a  cell  wall— 
and  will  be  a  separate  corpuscle  containing  a  nucleus,  in 
fact  a  cell.  Such  a  cell  however  has  not  come  into  being  as 
an  individual  unit  joined  to  its  like,  either  phylogenetically 
or  ontogenetically,  but  it  has  from  the  first  formed  a  part 
of  an  organic  whole,  of  which  it  is  nothing  more  than  a 
specialised  component  part. 

One  looks  naturally  for  evidence  of  this  mode  of  forma- 
tion of  cellular  structure  in  developing  Metazoa.  The  best 
evidence  is  to  be  found,  I  think,  in  the  segmentation  and 
formation  of  the  layers  in  many  Ccelenterata.  In  some 
Ccelenterata — for  example,  in  Renilla — the  nucleus  divides 
without  accompanying  division  of  the  cytoplasm  until  eight 
or  sixteen  nuclei  are  present,  and  then  the  cytoplasm 
divides  and  eight  or  sixteen  cells  are  formed.  But  of  more 
importance  than  this  is  the  formation  of  the  layers.     From 


316  SCIENCE  PROGRESS. 

the  considerations  stated  above  we  should  expect  that  the 
changes  in  chemical  composition  of  the  cytoplasm  and  the 
correlated  changes  in  the  nucleus,  in  other  words  the  dif- 
ferentiation, would  first  become  manifest  in  the  peripheral 
parts  of  the  growing  ccenocyte,  and  that  we  should  have  a 
stage  in  which  there  was  a  cellular  external  layer  and  a 
ccenocytial  internal  mass.  We  find  that  in  fact  in  the 
embryoes  of  many  Ccelenterates  the  outer  layer  is  divided 
up  early  into  sharply  defined  cells  at  an  early  period,  whilst 
the  central  cells  retain  the  character  of  a  ccenocytium  ;  at 
most  the  cell  outlines  of  the  internal  mass  are  confused  and 
indistinct. 

We  see  also  that  in  the  growing  tissues  of  the  embryoes 
of  higher  animals  the  embryonic  tissue  is  not  cellular  but  is 
a  ccenocytium,  for  example,  the  mesoblast  of  Avian  and 
Selachian  embryoes  and  of  the  Rabbit.  It  is  only  at  a  later 
stage  when  different  relations  to  other  parts  of  the  body 
have  been  acquired  and  new  exchanges  of  material  are 
forced  upon  the  growing  mass,  that  the  continuous  mass  of 
cytoplasm  is  split  up  into  corpuscles,  each  of  which,  in  my 
view,  corresponds  to  the  limit  of  influence  of  a  nucleus. 

On  the  other  hand  we  have  the  undoubted  fact  that  in 
many  organisms  there  is  no  ccenocytial  phase  in  develop- 
ment, but  the  cytoplasm  surrounding  the  nuclei  as  they  are 
successively  formed  is  immediately  marked  off  into  definite 
corpuscles,  so  that  the  whole  process  of  development 
suggests  the  formation  of  an  aggregate  of  bionts  derived  by 
division  from  a  single  parental  biont.  An  explanation  of 
this  fact  presents  many  difficulties,  and  I  have  not  now 
the  space  to  discuss  these  difficulties  and  to  show  that, 
obscure  as  the  subject  still  is,  there  is  ground  for  supposing 
that  the  difficulties  are  chiefly  due  to  the  prepossession 
which  exists  in  most  minds  in  favour  of  the  independent 
life  unit  theory.  I  hinted  in  my  previous  paper  (loc.  ciL,  p. 
171)  that  the  discrete  condition  of  the  blastomeres  of  so 
many  embryoes  may  be  connected  with  the  fact  that  they 
are,  from  the  very  outset,  specialised.  This  means  that  as 
the  nucleus  is  in  some  way  associated  with  the  transmission 
of  historic  qualities,  these  qualities  may  be  located  in  special 


THE  PRESENT  POSITION  OF  CELL-THEORY.     317 

parts  of  the  nucleus,  and  on  division,  some  of  the  daughter 
nuclei  may  possess  one  set,  others  may  possess  another  set 
of  "  qualities  ".  By  "  qualities  "  I  conceive  that  we  mean 
different  chemical  constitutions,  and  it  would  follow  that  the 
daughter  nuclei,  being  of  diverse  chemical  constitutions, 
would  react  in  diverse  manners  on  the  adjacent  protoplasm 
and  would  each  cause  the  delimitation  of  a  territory  of 
cytoplasm  within  the  limits  of  its  own  sphere  of  influence  ; 
in  other  words,  cell  bodies  would  be  formed  round  nuclei  of 
different  chemical  constitutions. 

There  is,  however,  yet  another  consideration  to  be  taken 
into  account.  As  Hertwig  has  shown,  the  cytoplasm  in 
many  ova  is  not  homogeneous  but  is  obviously  separable 
into  tracts  of  unquestionably  different  chemical  constitution. 
This  is  conspicuously  evident  in  the  ova  of  Amphibia.  As 
the  nucleus  divides,  its  products  come  into  relation  with 
different  kinds  of  cytoplasm  and  the  exchanges  between 
nucleus  and  cytoplasm  will  be  different  in  different  places 
within  the  limits  of  the  egg.  Arguing  on  the  same  prin- 
ciples as  before,  we  may  attribute  the  successive  formation 
of  discrete  blastomeres  to  this  factor  as  much  as  to  the 
separation  in  the  course  of  division  of  different  qualities 
contained  in  the  egg  nucleus,  and  according  as  one  leans 
towards  an  epigenetic  or  an  evolutionary  theory  of  develop- 
ment so  will  one  be  disposed  to  lay  more  stress  on  the 
one  factor  or  the  other.  There  is  this  much  to  be  said, 
that  the  most  remarkable  cell-lineages  (which  are  only 
traceable  when  the  blastomeres  are  discrete)  have  been 
observed  in  ova  which  contain  a  considerable  proportion  of 
yolk,  which  is  not  evenly  distributed  throughout  the  egg, 
and  it  is  suggestive  that  segmentation  in  all  cases  leads  to 
the  segregation  of  corpuscles  richer  in  yolk  from  corpuscles 
poorer  in  yolk — in  fact  to  the  segregation  of  materials  of 
diverse  chemical  constitution. 

Tempting  as  it  is  to  pursue  this  subject  further,  I  must 
not  attempt  to  do  it  now.  But  as  I  have  claimed  that  the 
views  which  I  have  tentatively  put  forward  are  agreeable 
to  the  facts  which  we  are  in  possession  of,  I  may  well  give 
a  short  summary  of  the  facts  which  I  have  relied  upon. 


318  SCIENCE  PROGRESS. 

( i )  The  co-existence  of  two  substances  at  least,  nuclein 
and  cytoplasm,  is  requisite  for  life.  (This  is  an  inference, 
strictly  speaking,  and  not  a  fact ;  but  I  think  that  it  may  be 
considered  a  legitimate  inference  from  what  we  know  of  the 
structure  of  the  lowest  bionts,  and  from  the  experiments  of 
Nussbaum,  Gruber,  Verworn  and  others.) 

(2)  The  existence  of  bionts,  such  as  Bacteria,  in  which 
we  are  unable  to  distinguish  more  than  these  two  sub- 
stances. (This  is  a  fact,  which  lends  material  support  to 
the  above  inference.) 

(3)  The  existence  of  bionts  in  which  nuclein  and  cyto- 
plasm are  not  indefinitely  intermingled,  but  the  former  is 
segregated  in  the  form  of  particles  scattered  through  the 
protoplasm,  e.g.,  Trachelocerca  phcenicopterus  and  Chcenia 
teres.  (We  gather  from  this  fact  that  the  two  chemical 
substances  tend  to  become  separated  from  one  another.) 

(4)  The  temporary  aggregation  of  nuclein  particles  to 
form  a  centralised  nucleus  for  the  purpose  of  the  repro- 
ductive act,  e.g.,  Holosticha  scutellwm.  (We  infer  from  this 
that  there  is  some  connection,  at  present  hidden  from  us, 
between  the  nucleus  and  the  reproductive  act.) 

(5)  The  existence  of  many  bionts  in  which  the  nuclein 
is  concentrated  to  form  a  nucleus.  (We  infer  that  this 
is  a  grade  of  permanent  differentiation  arising  out  of 
the  previous  temporary  grade.) 

(6)  The  existence  of  many  nuclei  in  all  bionts  which, 
whilst  still  undivided  as  regards  their  cytoplasm,  attain  to  a 
certain  size.  (From  this  we  infer  that  the  "  limit  of  nuclear 
influence "  cannot  extend  through  a  large  mass  of  cyto- 
plasm.) 

(7)  The  origin  of  "cellular"  tissues  from  a  ccenocytial 
mass,  e.g.,  the  endosperm  of  Phanerogams;  the  neural 
crest  of  certain  Vertebrate  embryoes ;  the  embryoes  of 
Arthropods;  the  mesoblast  of  many  Vertebrates,  etc.  (From 
this  we  infer  that  the  cells  composing  many  tissues  of  higher 
animals  are  not  to  be  regarded  as  bionts,  but  are  secondarily 
derived  during  the  growth  and  extension  of  the  parts  of  a 
single  biont.) 

This  re'sume  suffices   I  think   to   show  that  this  at   least 


THE  PRESENT  POSITION  OF  CELL-THEORY.     319 

may  be  claimed  for  the  views  which  I  have  put  forward. 
They  are  founded  strictly  on  the  facts,  and  they  do  not 
depend  on  the  assumption  of  any  kind  of  hypothetical  units 
of  which  the  nature  and  even  the  very  existence  is  entirely 
beyond  our  ken. 

Since  I  have  not  been  able  to  develop  my  views,  I 
cannot  but  expect  that  they  will  be  subject  to  considerable 
modification  and  even  to  entire  overthrow.  They  form  at 
least  an  attempt  to  classify  and  colligate  the  various  pheno- 
mena which  seem  to  be  germane  to  the  subject,  and  I  have 
collected  and  compared  a  much  larger  body  of  facts  than  I 
am  here  able  to  refer  to,  without  finding  any  which  are 
contradictory  to  my  ideas.  That  my  ideas  are  somewhat 
indistinct  need  not,  at  present,  be  urged  as  an  objection,  for 
indistinctness  is  not  necessarily  a  sign  of  falsity.  The  cell- 
republic  theory  was  not  wanting  in  distinctness,  but 
it  was  inappropriate  to  the  facts.  I  only  claim  that  my 
ideas  are  appropriate,  and  I  shall  hope  to  give  them  more 
distinctness  on  a  future  occasion. 

In  the  meantime  I  leave  out  of  consideration  a  large 
question,  concerning  which  I  think  it  scarcely  possible  to 
give  a  satisfactory  account,  in  this  standing  in  opposition  to 
Mr.  Sedgwick,  who  thinks  that  which  I  have  attempted  to 
be  impossible,  but  offers  a  solution  of  that  which  I  think 
scarcely  possible. 

The  question  is,  how  are  we  to  account  for  that  pheno- 
menon which  I  have  described  as  a  progress  from  the  state 
of  an  independent  corpuscle,  through  a  state  of  many  coherent 
or  continuous  or  conjunct  interdependent  corpuscles,  back 
again  to  the  state  of  a  single  independent  corpuscle  ? 

Mr.  Sedgwick's  solution  is  this  :  that  the  unicellular 
form  is  assumed  by  metazoa  in  order  that  conjugation  may 
be  possible.  The  single  independent  corpuscle  which  re- 
curs in  the  cycle  is  the  sexual  cell,  and  the  essential  feature 
of  sexual  reproduction  is  the  conjugation  of  reproductive 
cells.  The  unicellular  phase  is  only  assumed  in  sexual,  not 
in  asexual  reproduction,  and  this  is  to  be  explained  by  the 
consideration  that  conjugation  is  as  necessary  in  metazoan 
life  as  in  protozoan  life,  but   that  conjugation  between  the 


320  SCIENCE  PROGRESS. 

ordinary  forms  of  metazoa  is  impossible  for  mechanical 
reasons,  and  therefore  special  individuals  of  a  form  simple 
enough  to  admit  of  conjugation  are  produced.  These 
special  individuals  are  the  ovum  and  spermatozoon. 

The  explanation  is  extremely  ingenious  and  there  is 
nothing  unreasonable  in  it,  but  one  cannot  say  that  it  is 
altogether  acceptable  at  first  sight.  It  would  have  been 
more  satisfying  if  Mr.  Sedgwick  had  marshalled  some  of 
the  facts  relative  to  the  sexual  reproduction  of  some  of  the 
lowest  multicellular  organisms  and  had  shown  their  rela- 
tion to  his  suggestion.  A  difficulty  which  at  once  occurs 
to  me  is  that  in  many  plants  asexual  reproduction  is 
effected  through  the  agency  of  a  single  cell.  In  fact, 
before  one  can  accept  any  solution  of  the  question  one 
requires  a  very  extensive  and  careful  survey  of  all  the  facts 
known  about  the  reproduction  of  the  lower  plants.  They 
afford  examples  of  every  conceivable  grade  of  the  reproduc- 
tive processes,  and,  once  one  begins  to  look  into  the  subject, 
hints  as  to  the  parting  of  the  ways  of  sexual  and  asexual 
reproduction  occur  to  one  at  every  step.  The  pity  is  that 
the  mere  zoologist,  who  does  not  find  such  a  fruitful  field  in 
his  own  territory,  is  obliged  to  disinter  the  facts  from  the 
load  which  the  peculiarities  of  botanical  terminology  have 
heaped  upon  them. 

It  is  quite  possible,  however,  that  such  a  survey  would 
afford  strong  support  to  Mr.  Sedgwick's  opinions,  and  if  it 
should  do  so  they  would  in  no  way  be  inconsistent  with 
the  ideas  which  I  have  put  forward,  but  would  rather  sup- 
port them. 

A  word  in  conclusion  for  those  who  will  reproach  me 
for  having  attempted  to  frame  a  chemico-physical  theory 
of  organic  growth,  and  for  having  used  such  phrases  as 
"  complex  chemical  constitution,"  "  exchange  of  chemical 
material,"  etc.,  without  assigning  any  distinct  meaning 
to  them.  I  admit  that  our  knowledge  on  the  subject 
is  rather  inadequate,  and  that  I  have  used  obscure  phrases 
to  express  relations  which  are  in  themselves  obscure.  If 
one  attempts  to  lift  the  veil  of  obscurity  one  must  inevitably 


THE  PRESENT  POSITION  OF  CELL-THEORY.     321 

call  hypothesis  to  aid,  and  it  has  been  my  object  to  avoid 
the  use  of  hypothesis  where  I  could  do  without  it.  It  is, 
however,  legitimate  to  frame  an  argument  which,  while  it 
agrees  with  the  lessons  of  experience,  is  ultimately  based 
upon  hypothetical  considerations,  provided  always  that  those 
considerations  are  consistent  with  the  accepted  teaching  of 
the  sciences  whose  aid  is  invoked. 

Any  attempt  whatever  to  find  an  explanation  of  vital 
phenomena  ends  in  an  appeal  to  chemistry  and  physics. 
Knowing  as  we  do  that  the  elements  of  which  organic 
bodies  are  composed  are  not  different  from  those  which 
occur  in  the  inorganic  world,  we  cannot  refuse  to  acknow- 
ledge that  vital  processes  are  in  the  end  chemico-physical 
processes,  and  this  much  is  conceded  by  every  author  of  a 
theory  of  vital  units.  The  difficulty  which  they  have  to 
face  is  the  same  as  that  which  I  have  to  face,  and  is  not  one 
whit  the  less  because  it  is  compressed  into  the  limits  of 
a  biophor,  whereas  I  would  allow  it  the  limits  of  a  cell. 
Can  we  frame  any  distinct  ideas  of  these  chemico-physical 
processes  ?  Not  very  distinct  ideas,  perhaps,  yet  we  can 
supplement  the  lack  of  positive  evidence  by  analogies  and 
illustrations  involving  the  same  ideas  as  those  which  are 
current  in  the  physical  world. 

It  was  Professor  W.  K.  Clifford,  I  think,  who  first  drew 
a  graphic  picture  of  the  molecular  forces  which  are  at  work 
in  any  chemical  compound,  by  describing  the  atoms  as 
linked  to  one  another  and  dancing  a  sort  of  merry-go-round 
within  circumscribed  limits.  We  may  carry  on  the  illustra- 
tion, which,  fanciful  though  it  may  seem,  is  supported  by 
physical  and  mathematical  considerations.  A  biont  is  a 
great  organised  war  dance,  performed  by  a  whole  army 
corps.  The  individuals  composing  each  company  are  the 
atoms,  they  are  linked  to  one  another  by  companies  and 
each  company  dances  its  own  figure.  Every  company  is  a 
molecule,  and  every  company  dance  is  but  a  part  of  a  larger 
dance,  in  which  the  companies  act  in  relation  to  one  another 
as  the  individuals  act  in  the  company  dance.  The  larger 
dances  are  regimental  dances  and  every  regiment  is  a 
micella.      The  regimental  dances  are  but  parts  of  still  larger 


322  SCIENCE  PROGRESS. 

brigade  dances,  and  the  brigade  dances  are  but  part  of  the 
great  dance  of  the  whole  army  corps,  which,  taken  as  a 
whole,  is  the  biont.  The  illustration  is  not  quite  exact,  for 
each  company  must  not  be  considered  as  consisting  of  like 
individuals,  but  of  many  individuals  of  all  arms,  some  like 
and  some  unlike,  linked  in  such  various  ways  that  no  two 
companies  are  the  same,  partly  because  of  the  proportions  of 
different  kinds  of  individuals  composing  them,  partly  because 
of  the  way  in  which  those  individuals  are  linked  together. 
Nor  must  we  imagine  that  individuals  are  permanently 
attached  to  companies,  nor  yet  companies  to  regiments,  but 
that  in  the  course  of  the  dance  individuals  are  passed  from 
company  to  company,  and  companies  from  regiment  to 
regiment,  each  conforming  temporarily  to  the  particular 
figure  of  that  part  of  the  dance  to  which  he  or  it  for  the 
time  belongs.  Further  than  this  the  individuals  engaged 
in  the  whole  dance  are  never  lone  the  same  :  there  are 
bystanders  who  for  a  time  do  not  participate  in  the  dance 
but  are  caught  up  one  by  one,  whirled  through  the  figures, 
passed  from  company  to  company,  from  regiment  to  regi- 
ment and  brigade  to  brigade,  and  are  eventually  passed  out 
of  the  dance  again,  after  having  participated  in  some  or  all 
of  the  figures  as  the  case  may  be.  Every  individual  in  the 
dance  is  at  some  time  passed  out  of  the  dance,  becomes 
a  bystander,  and  may  again  be  caught  up  and  whirled  along 
in  the  dance  once  more. 

The  illustration  is  farfciful,  if  you  please,  but  it  is  of  the 
same  kind  as  illustrations  used  to  depict  the  play  of  mole- 
cular forces  in  the  inorganic  world.  It  serves  a  purpose  in 
that  it  gives  the  imagination  something  to  work  upon,  and 
it  enables  one  to  conceive  of  the  immense  complexity  which 
is  possible  in  a  chemico-physical  process.  The  army  dance 
which  I  describe  is  capable  of  any  number  of  combinations, 
a  number  amply  sufficient  to  satisfy  the  needs  of  those  who 
insist  so  strongly  on  the  marvellous  complexity  of  life. 
Let  anybody  imagine  an  army  to  be  composed  of  four 
brigades,  each  brigade  of  four  regiments,  each  regiment  of 
ten  companies,  and  each  company  to  contain  100  indi- 
viduals   of    the    eight    kinds,    carbon,    oxygen,    hydrogen, 


THE  PRESENT  POSITION  OF  CELL-THEORY.     323 

nitrogen,  sulphur,  phosphorus,  potassium  and  iron,  in 
varying  proportions,  and  let  him  work  out  the  possible 
combinations.  I  think  he  will  be  satisfied  with  the  com- 
plexity. 

What  then  of  heredity  and  of  the  capacity  which  I  have 
mentioned  for  acquiring  historic  qualities  ? 

Believing  as  I  do  that  the  vital  processes  must  in  the 
end  be  attributed  to  a  particular  mode  of  molecular  motion, 
I  believe  that  it  is  the  form  of  movement  which  is  trans- 
mitted. Returning  to  my  illustration  I  would  say  that  it  is 
the  figure  of  the  whole  dance  which  makes  up  the  species, 
and  that  it  is  the  figure — the  mode  of  motion — which  is 
inherited,  clearly  not  the  individuals  engaged  in  the  dance, 
except  in  a  very  small  degree,  for  they  are  constantly 
coming  into  the  dance  anew  and  as  constantly  being  passed 
out  of  it.  Under  certain  circumstances  there  may  be  an 
excess  of  one  or  more  kinds  of  new  individuals  pressing  into 
one  part  of  the  dance  which  will  affect  the  figure  of  the 
company  dance  which  they  crowd  into,  and  this  will  affect 
regimental  figures  and  ultimately,  in  decreasing  degrees, 
the  whole  army  figure.  In  this  way  we  may  picture  to 
ourselves  the  action  of  external  influences  in  bringring  about 
variation.  But  I  have  given  rein  enough  to  my  imagina- 
tion. The  picture  was  introduced  partly  to  show  that 
beneath  my  obscure  phrases  there  was  some  distinctness  of 
ideas,  partly  to  emphasise  the  immense  complexity  of 
Nature  and  to  show  that  even  atoms  and  molecules  may  be 
conceived  to  be  so  combined  together  that,  in  Goethe's 
words,  "  sie  bewirken  so  eine  unendliche  Production  aut 
alle  Weise  und  nach  alien  Seiten  ". 

Gilbert  C.   Bourne. 


THE    HEREDITARY   TRANSMISSION    OF 
MICRO-ORGANISMS. 

IT  is  well  known  that  in  the  construction  of  many  of  the 
theories  of  heredity  the  doctrine  of  the  transmission  of 
acquired  characters  has  obtained  considerable  prominence. 
The  hypothesis  of  Lamarck  rendered  it  necessary  to  assume 
that  structural  characters  which  had  arisen  from  the  use  or 
disuse  of  organs,  became  an  integral  part  of  the  individual 
and  reappeared  in  the  descendants,  and  although  the  appli- 
cation   of   this    idea    became    greatly   restricted   when    the 
principle   of  natural   selection   was    established,    it    is    only 
within  the  last  few  years  that  the  transmission  of  acquired 
characters  has  been  considered  as  unproven,  and  the  in- 
stances put  forward   in  support  of  this  view  to  be  capable 
of  a  different  explanation.      It  may  be  admitted  that  mutila- 
tions and  permanent  injuries  can  be  included  among  acquired 
characters,  and  the  structural  and  functional  modifications  of 
the   individual   which    occur    in    disease    may  persist,    and 
therefore  also  be    considered  as  definite  morphological  or 
physiological  changes.      Mutilations  apparently  do  not  pass 
from  parent  to  offspring,  and  this  has  been  especially  pointed 
out  by   Weismann  and  his  followers,   since,   if  heredity  is 
capable  of  explanation  on  the  hypothesis  of  the  continuity 
of  germ-plasm  contained  in  definite  reproductive  cells,  any 
change  in  the  structure  or  modes  of  activity  of  the  essential 
body  or  somatic  cells  would  not  be  transmitted.     An  iden- 
tical line  of  argument  also  negatives  the  belief  that  diseases 
can  be  inherited,  and  this  view  was  maintained  by  Weismann 
in  his  well-known  criticism  on  the  transmission  of  experi- 
mental epilepsy ;  the  symptoms  in  this  hereditary  disease  he 
considered  might  be  due  to  some  unknown  microbe   which 
found    its    nutritive    medium    in    the    nervous    tissues    and 
was  transmitted   in   the  reproductive  cells.      The   question 
whether  micro-organisms  can  actually  pass  from  parent  to  off- 
spring is  one  which  has  been  carefully  investigated,  whereas 


TRANSMISSION  OF  MICRO-ORGANISMS.  325 

the  proof  that  actual  morphological  changes,  such  as  modi- 
fications of  histological  or  molecular  structure,  can  be  trans- 
mitted has  not  yet  been  given.  It  is  conceivable  that 
predispositions  may  be  inherited,  and  these  must  result 
from  alterations  in  the  germ-plasm,  or  a  direct  infection  of 
the  germ  or  embryo  might  cause  the  transference  of  a  dis- 
ease from  one  generation  to  another,  a  phenomenon  which 
simply  depends  upon  a  particular  mode  of  conveyance  of  a 
parasite.1 

In  many  diseases,  and  particularly  those  which  are  directly 
caused  by  micro-organisms,  it  is  a  matter  of  interest  to  note 
the  wide  differences  which  exist  between  the  conveyance 
of  hereditary  characters,  and  of  a  specific  disease.  Armauer 
Hansen  (1)  has  made  this  perfectly  clear  in  considering  the 
etiology  of  leprosy.  He  has  pointed  out  that  true  heredi- 
tary characters  are  usually  limited  to  one  sex,  frequently 
appear  at  a  particular  age,  and  the  phenomenon  of  atavism 
is  not  rare  ;  but  in  the  conveyance  of  such  a  disease  as 
tuberculosis  or  leprosy,  none  of  these  conditions  are  ful- 
filled. It  is  a  logical  deduction  from  the  consideration  of 
these  differences  that  every  specific  disease  which  is  trans- 
mitted cannot  be  regarded  as  hereditary,  but  as  an  instance 
of  the  direct  bacterial  infection  of  the  germ-cells  or  embryo. 
Most  writers  on  cancer  and  malignant  growths  have  dis- 
cussed the  hereditary  transmission  of  this  disease,  and  if  it 
is  allowed  that  a  disposition  to  cancer  may  be  derived  by 
inheritance,  then  this  condition  would  depend  upon  some 
peculiarity  inherent  in  the  nucleus  of  the  germ-cells  ;  but 
if,  on  the  other  hand,  malignant  disease  is  caused  by  a 
parasite  belonging,  as  some  investigators  have  sought  to 
prove,  to  the  group  of  protozoa  or  protophyta,  then  the 
transmission  of  the  actual  disease  will  depend  upon  the 
passage  of  a  micro-organism  which  invades  the  germ  or  its 

1 "  Pour  les  maladies,  vraiement  constitutionnelles,  c'est  la  substance 
hereditaire  elle-meme  qui  est  viceuse;  pour  les  maladies  infectieuses,  levice 
n'est  pas  dans  la  substance  elle-meme,  mais  a  cote  d'elle,  et  les  produits 
sexuels  servent  seulement  de  vehicule  a  un  parasite  capable  d'engendrer 
plus  tard  une  maladie  generate. "  Y.  Delage,  La  Structure  du  Protoplasma 
et  les  Theories  sur  F  Heredite.     Paris,  1895. 


326  SCIENCE  PROGRESS. 

product,  and  the  whole  phenomenon  ceases  to  be  one  of 
heredity,  for  the  hereditary  transmission  of  micro-organisms 
is  simply  a  particular  instance  of  bacterial  infection.  The 
inheritance  of  actual  specific  disease  must  therefore  always 
be  considered  as  a  problem  absolutely  distinct  from  that 
of  heredity  and  incapable  of  explanation  by  any  hypothesis 
of  heredity. 

Micro-organisms  which  reach  an  individual  either  by 
inheritance  or  other  modes  of  conveyance  may  undoubtedly 
exhibit  a  period  of  latent  life  extending  over  many  years  ; 
but  when  this  condition  is  succeeded  by  an  active  life,  to 
establish  the  proof  of  an  hereditary  transmission  is  ex- 
ceedingly difficult  or  even  impossible  (11).  The  early 
researches  into  problems  of  this  nature  were  necessarily 
made  with  the  help  of  statistical  and  clinical  methods  ;  but 
it  is  the  application  of  experimental  methods,  which  could 
only  be  pursued  with  success  as  the  study  of  bacteriology 
developed,  that  has  finally  succeeded  in  removing  the  subject 
of  the  hereditary  transmission  of  specific  diseases  from  the 
hazy  region  of  speculation.  The  attitude  assumed  by 
Baumgarten  and  his  followers  on  this  question  is  well 
known.  In  the  case  of  tuberculosis  it  is  maintained 
that  individuals  are  rarely  infected  with  tubercle  bacilli 
after  birth,  but  that  the  disease  in  the  majority  of  cases  is 
due  to  a  parasitic  infection  of  the  egg-cell  or  embryo.  It 
is  even  urged  that  the  bacilli  may  remain  latent  in  one 
individual,  and  only  enter  upon  a  phase  of  activity  in  the 
offspring,  a  view  which,  if  correct,  would  accord  with  the 
opinion  of  many  clinical  observers.  While  destroying  the 
opinion  so  commonly  held  that  an  "inherited  tubercular 
predisposition  "  exists,  Baumgarten's  theory  of  hereditary 
parasitism  makes  a  still  greater  demand  on  the  imagina- 
tion ;  but  that  the  views  of  this  distinguished  pathologist 
have  acted  as  a  stimulus  to  renewed  experimental  work  on 
the  transmission  of  micro-organisms  is  beyond  doubt. 
Recent  papers  by  O.  Lubarsch  (2)  of  Rostock  and  J. 
Csokor  (3)  of  Vienna  give  an  admirable  exposition  of  the 
present  position  of  our  knowledge  on  this  subject  of  the 
transference  of  bacteria  from  parent  to  offspring  in  man  and 


TRANSMISSION  OF  MICRO-ORGANISMS.  327 

the  lower  animals,  and  the  evidence  that  bacteria  may  in 
this  manner  gain  access  to  the  organism  is  incontestable. 

In  inherited  specific  diseases  it  is  possible  to  distinguish 
two  forms  of  infection  :  first,  by  a  direct  bacterial  invasion  of 
the  essential  reproductive  cells  ;  secondly,  the  egg-cell  or 
the  embryo  may  receive  micro-organisms  from  the  female, 
in  which  case  the  blood  stream  is  the  channel  for  conveyance, 
and  the  whole  phenomenon  is  then  one  of  metastasis  com- 
parable in  every  respect  to  what  obtains  when  bacteria 
multiply  at  a  definite  area  of  the  body,  and  thence  become 
distributed  by  the  blood  and  lymph  in  distant  parts  of  the 
organism.  Bacterial  infection  may  therefore  be  either 
germinative  or  placental,  and  in  mammals  the  latter 
form  of  transmission  is  not  infrequently  observed.  The 
specific  bacteria  of  anthrax,  typhoid  fever  (6),  pneumonia 
and  tuberculosis  (7)  have  been  isolated  from  the  human  foetus, 
cultivated,  and  successfully  inoculated  upon  animals,  so 
that  the  chain  of  evidence  is  complete.  The  pyogenic 
cocci  such  as  streptococcus  pyogenes  (24)  and  staphylococcus 
pyogenes  aureus  have  also  been  demonstrated  in  foetal 
tissues  by  Fraenkel  and  Kiderlen,  and  Auche  has  shown 
that  in  small-pox  the  placenta  may  be  penetrated  by  these 
micro-organisms.  In  the  lower  animals  not  only  may  the 
bacteria  already  mentioned  be  transmitted,  but  also  those  of 
cholera,  glanders  and  chicken  cholera. 

In  many  animals  the  egg-cell  is  the  largest  unit  of  the 
organism,  and  would  be  capable  of  containing  numberless 
bacteria  ;  that  such  an  infection  does  occur  was  first  estab- 
lished by  the  classical  observations  of  Pasteur  (4),  which 
have  been  confirmed  by  all  subsequent  investigators.  In 
pebrine,  a  disease  of  silk-worms,  definite  sporocyst  forms 
(microsporidia  or  Cornalia's  corpuscles)  are  transmitted  from 
the  imago  in  the  egg-cell,  and  the  larva  is  directly  infected 
in  this  manner.  Blochmann  (5)  has  also  described  a  similar 
mode  of  conveyance  of  bacteria  in  the  ova  of  Blatta 
orientalis.  In  a  single  instance  a  tubercle  bacillus  has 
been  seen  in  the  mammalian  ovum.  The  sperm-mother- 
cells  may  also  be  invaded  by  micro-organisms,  but  this  is 
rare,  and  no  example  of  an  infected  male  reproductive  cell 


328  SCIENCE  PROGRESS. 

exists.  That  this  condition  will  ever  be  demonstrated  is 
improbable,  since  bacteria  contrast  with  parasitic  protozoa 
in  infecting  the  cell  and  sparing  the  cell-nucleus,  and  the 
essential  agent  in  the  process  of  fertilisation  is  the  nucleus 
or  head  of  the  sperm-cell. 

Various  observers  have  attempted  a  solution  of  this 
question  of  germinative  infection  by  the  employment  of 
two  different  methods.  The  first  of  these  is  that  pursued 
by  Mafifucci,  who  directly  infected  the  fertilised  eggs  of  the 
fowl,  and  in  the  second  not  only  were  the  genital  glands 
and  the  products  of  these  examined  for  micro-organisms, 
but  pieces  of  them  were  taken  from  animals  suffering  with 
specific  diseases  and  used  as  material  for  inoculation. 

Even  if  it  is  assumed  that  an  ovum  actually  is  a  site  in 
which  bacilli  such  as  those  of  tuberculosis  exist,  it  may  be 
objected  either  that  the  microbe  is  dead,  or  that  such  a  cell 
is  incapable  of  development.  This  is  the  attitude  taken  by 
Virchow,  who  absolutely  denies  the  existence  of  congenital 
tuberculosis.  Maffucci's  experiments,  however,  contra- 
dict this  opinion,  for  this  observer  has  shown  that  the 
bacilli  of  avian  tuberculosis  develop  in  an  infected  embryo, 
and  the  chicken  succumbs  to  tuberculosis  in  twenty  days 
to  four  and  a  half  months  after  hatching.  If,  however, 
instead  of  infecting  the  embryo,  bacteria  such  as  those  of 
chicken  cholera,  or  anthrax,  or  Friedlander's  pneumococcus 
are  introduced  in  the  extra-embryonic  area,  then  these 
organisms  may  actually  enter  the  embryo  through  the 
allantois  but  do  not  increase  in  number  provided  the 
embryo  remains  alive.  The  pathogenic  micro-organisms 
may  therefore  be  destroyed  or  attenuated  by  actively  pro- 
liferating embryonic  tissue  cells,  or  they  may  become  capable 
of  development  at  a  later  period  of  life,  in  other  words, 
remain  latent.  Although  these  experiments  were  devised 
to  establish  the  view  that  a  genuine  germinative  infection 
may  occur,  they  obviously  do  nothing  of  the  kind,  and  it  is 
to  the  researches  of  Gartner  that  we  owe  an  absolute 
demonstration  that  ova  may  contain  pathogenic  germs. 
Gartner  among:  other  animals  inoculated  canaries  with  mam- 
malian  tubercle  bacilli.     After  a  few   weeks    he   removed 


TRANSMISSION  OF  MICRO-ORGANISMS.  329 

nine  eggs,  washed  these  in  dilute  corrosive  sublimate, 
dried  them  in  wool  and  introduced  the  contents  of  each  eo-or 
into  the  peritoneal  cavity  of  guinea-pigs.  In  two  cases 
tuberculosis  was  set  up,  the  animals  dying  one  and  a  half 
months  and  two  and  a  half  months  after  infection.  These 
experiments,  which  are  absolutely  free  from  objection, 
conclusively  prove  that  the  egg-cell  may  contain  virulent 
bacteria,  and  it  is  easily  conceivable  that  such  eggs  may 
develop  and  the  transmission  of  the  parasite  take  place  by 
direct  germinative  infection,  especially  since  Maffucci's 
work  shows  that  such  infected  eggs  are  capable  of  develop- 
ment. 

Jani,  Westermayer,  Spano,  Walther,  Gartner,  and  quite 
recently  Jakh,  have  microscopically  investigated  the  bac- 
terial contents  of  the  reproductive  glands,  and  also  inoculated 
animals  with  fragments  of  these  organs.  With  the  exception 
of  Gartner's  researches  these  experiments  have  not  added 
greatly  to  our  knowledge  of  the  hereditary  transmission  of 
bacteria.  All  the  experiments  of  Westermayer  were  nega- 
tive. In  fourteen  cases  of  well-marked  General  tuberculosis 
no  tubercle  bacilli  could  be  recognised,  and  inoculation 
experiments  were  failures.  The  experiments  of  Jakh  (10) 
were  more  fortunate.  Five  inoculations  with  pieces  of  the 
male  reproductive  gland  and  its  product,  taken  from  in- 
dividuals dead  of  tuberculosis,  gave  three  positive  results. 
If  the  gland  alone  was  used,  the  experiments  were  always 
negative,  and  of  three  inoculations  with  pieces  of  the  egg- 
forming  gland  one  was  successful.  It  may  be  admitted  that 
these  experiments  do  not  really  throw  much  light  on  the 
subject  of  germinative  infection,  but  Gartner's  researches 
are  of  much  greater  value.  He  experimented  upon  mice, 
guinea-pigs,  rabbits,  and  canaries,  these  birds  being  sus- 
ceptible to  mammalian  tubercle  bacilli.  Having  inoculated 
these  animals  with  bacillus  tuberculosis,  a  careful  examination 
was  made  of  the  offspring  of  such  tubercular  parents.  This 
method  might  naturally  be  expected  to  give  a  conclusive 
answer  to  the  question  of  hereditary  infection,  and  the 
following  information  has  been  gained  from  these  researches : 
1.     The    sperm    rarely    contains    tubercle    bacilli — five    in 

23 


330  SCIENCE  PROGRESS. 

thirty-two  cases.  Even  if  micro-organisms  exist  they  are 
incapable  of  infecting  the  egg.  In  twenty-two  (rabbits) 
and  twenty-one  cases  (guinea-pigs)  where  the  male  repro- 
ductive gland  was  the  seat  of  an  acute  tubercular  process, 
the  offspring  were  never  infected.  2.  Neither  does  the 
male  infect  the  female  by  way  of  the  sperm.  3.  Infection 
takes  place  frequently  from  the  female  to  the  foetus,  and  in 
an  overwhelming  majority  of  cases  by  way  of  the  placenta. 

A  few  considerations  may  make  the  importance  of  Gart- 
ner's work  more  evident.  If  bacilli  exist,  as  they  occasionally 
do,  in  the  product  of  the  male  gland  it  is  probable  that  this 
material,  like  other  parts  of  the  body,  contains  bacteria  only 
a  few  days  before  death,  for  we  know  that  quite  an  abnormal 
number  of  micro-organisms  may  invade  the  whole  organism 
during  the  last  days  of  life.  Tubercle  bacilli  are  immotile 
and  therefore  will  not  easily  reach  the  oviduct  or  egg,  a 
matter  of  some  importance,  since  it  has  been  shown  that  in 
most  cases  the  ovum  is  fertilised  either  high  up  in  the 
oviduct  or  even  at  the  time  of  liberation  from  the  Graafian 
follicle.  Stroganoff  (12)  has  also  pointed  out  that  the 
uterine  area  is  sterile,  and  the  secretion  of  this  is  bacteri- 
cidal, in  which  it  resembles  sputum  (13)  or  the  mucus  of  the 
nasal  tract  which  is  almost  free  from  germs  (14).  Lastly,  it  is 
well  known  that  a  single  male  morphological  unit  is  sufficient 
for  fertilisation,  and  if  we  assume  with  Gartner  that  100 
virulent  tubercle  bacilli  are  mixed  with  sperm-cells,  the 
ratio  of  bacteria  to  these  would  be  about  1  :  22,500,000  ;  it 
is  hardly  conceivable  on  the  doctrine  of  probabilities  that  a 
bacillus  would  gain  access  to  the  egg.  It  may  therefore  be 
considered,  both  on  experimental  and  theoretical  grounds, 
that  a  germinative  infection  of  the  ovum  never  occurs  by 
the  conveyance  of  micro-organisms  in  the  male  reproductive 
cells. 

The  difficulties  which  exist  in  proving  that  the  in- 
heritance of  a  specific  disease  may  occur  through  an  in- 
fection of  the  ovum  are  fortunately  not  so  great  in  those  cases 
where  the  passage  of  micro-organisms  takes  place  solely 
from  the  female  to  the  fcetus  by  way  of  the  placenta.  It  is 
established  that  specific  micro-organisms  can  pass  by  this 


TRANSMISSION  OF  MICRO-ORGANISMS.  331 

route.  It  is  not  even  necessary  to  assume  that  there  is  any 
lesion  whatever  in  the  placenta  or  that  the  epithelium  of 
the  foetal  villi  is  destroyed.  An  experiment  by  Zuntz 
shows  clearly  that  particulate  material  will  easily  pass  into 
the  amniotic  fluid  from  the  maternal  portion  of  the 
placenta,  for  if  indigo-carmine  is  injected  into  the  veins 
of  the  female  the  dye  passes  into  the  amnion  leaving  the 
foetus  free,  and  in  this  very  manner  anthrax  bacilli  may 
pass,  and  from  the  amnion  gain  access  to  the  mouth  of 
the  foetus,  enter  the  gut  and  set  up  disease  by  a 
primary  infection  of  the  wall  of  the  intestine  (25).  An  intra- 
uterine infection,  therefore,  can  occur  without  lesion  of  the 
placenta,  though  in  the  majority  of  cases  this  structure  is 
primarily  infected,  and  then  the  foetus,  or  else  haemorrhages 
of  the  placenta  permit  the  passage  of  micro-organisms. 
However    the    undoubted    fact    that    micro-organisms    can 

o 

penetrate  the  healthy  skin  by  way  of  the  hair  follicles — and 
the  same  is  possibly  true  for  the  epithelium  of  the  urinary 
tract — must  not  be  forgotten  in  considering  the  passage  of 
bacteria  across  the  placenta.  This  structure  may  be  nor- 
mal and  even  then  allow  the  transit  of  bacteria.  Birch- 
Hirschfeld  (15)  from  researches  on  the  structure  of  the 
human  placenta  as  well  as  that  of  mice,  rabbits  and  goats 
considers  that  the  bacilli  of  anthrax  at  any  rate  can 
traverse  the  uninjured  chorionic  epithelium.  Moreover  in 
the  human  placenta  and  in  rabbits  numerous  processes  of 
the  chorion  traverse  the  placental  sinuses,  and  these  pro- 
cesses are  normally  destitute  of  epithelium.  It  was  noticed 
by  Max  Wolff  (16)  that  anthrax  bacilli  easily  pass  if  the 
placenta  was  crushed  or  torn,  and  micro-organisms  which 
exert  a  necrotic  influence  on  tissues,  such  as  the  pyogenic 
cocci,  appear  first  to  destroy  the  epithelium  of  the 
chorionic  villi,  and  then  pass  through  into  the  foetal 
blood.  In  this  fluid  micro-organisms  reach  the  liver,  and 
it  is  this  organ  which,  as  a  rule,  is  primarily  affected,  and 
then  the  glands  in  the  lymphatics  leading  from  the  organ 
become  implicated.  The  location,  therefore,  of  tubercles 
in  foetal  tuberculosis  is  characteristic,  and  all  observers 
insist  upon  this  feature  in  determining  whether  tubercular 


332  SCIENCE  PROGRESS. 

deposits  are  of  intra-  or  extra-uterine  origin  in  early  cases 
of  the  disease.  As  a  matter  of  interest  it  may  be 
mentioned  that  quite  recently  Bar  and  Renon  have  de- 
monstrated tubercle  bacilli  in  the  blood  of  the  umbilical 
vein  (7).  The  method  used  by  these  observers,  that  of 
inoculating  guinea-pigs  with  the  suspected  blood,  and  in 
this  manner  establishing  tuberculosis,  is  not  so  convincing 
as  the  actual  demonstration  of  bacteria  in  fcetal  tissues. 
Wassermann  (17)  in  a  recent  paper  especially  insists  on 
this  point,  and  discards  all  evidence  of  inherited  disease 
which  rests  simply  upon  inoculation  experiments.  He 
describes  a  case  of  early  tuberculosis  which  ended  fatally 
when  the  child  was  ten  weeks  old,  where  the  disease  was 
acquired,  not  from  the  parents  who  were  healthy,  but  by 
direct  infection  from  a  tubercular  relation,  and  believes  that 
such  cases  as  these  are  not  infrequently  cited  as  instances 
of  congenital  disease.  In  his  opinion  hereditary  trans- 
mission of  bacteria  does  occur,  but  it  is  exceedingly  rare 
in  comparison  with  the  frequency  of  extra-uterine  infection. 
Bernheim  (18)  considers  that  the  offspring  rarely,  if  ever, 
become  tubercular  if  separated  from  tubercular  parents, 
with  the  exception  of  those  cases  where  the  placenta  is 
infected.  The  case  reported  by  Ivan  Honl  (19)  of  a  child 
fifteen  days  old  that  on  autopsy  showed  tubercular  nodules 
in  the  liver,  spleen,  and  lungs,  and  numerous  bacilli, 
must  be  classed  as  a  definite  case  of  transmission  which  with 
many  others  lends  no  support  to  Eberth's  statement  that 
individuals  do  not  inherit  tuberculosis  but  acquire  it  (23). 

A  recent  case  of  congenital  typhoid  fever  is  related  by 
Freund  and  Levy  (20),  and  instances  of  transmitted  hemor- 
rhagic infection  have  been  recorded  by  Neumann  (21)  and 
by  Dungern  (22).  The  numerous  examples  which  the 
journals  of  veterinary  science  contain,  especially  the  work 
of  Bang,  Kockel,  and  Lungwitz,  also  afford  conclusive  evi- 
dence of  the  transmission  of  pathogenic  micro-organisms, 
though  there  is  a  consensus  of  opinion  that  the  placental 
is  far  more  frequent  than  the  germinative  infection.  The 
share  borne  by  the  male  in  this  transmission  may  be  dis- 
regarded, as  no  bacteriological  evidence  exists  to  support 


TRANSMISSION  OF  MICRO-ORGANISMS.  333 

this  view.  Finally,  the  frequency  of  hereditary  transmission 
of  pathogenic  germs  is  exceedingly  small  compared  to  other 
modes  of  infection. 


BIBLIOGRAPHY. 

(1)  HANSEN  and  LOOFT.     Leprosy  in  its  Clinical  and  Pathological 

Aspects,  1895. 

(2)  Lubarsch.      Ergebnisse  der  allgemeinen  Atiologie  der  Mens- 

chen-und  Tierkrankheiten,  by  Lubarsch  and  Ostertag,  p.  427, 
1896.  References  to  the  transmission  of  infectious  diseases 
to  descendants  will  be  found  in  this  and  the  following  paper. 
Some  additional  and  later  references  are  given  in  the  course 
of  this  article. 

(3)  Csokor.     Ibid.,  p.  456. 

(4)  Pasteur.     Etudes  sur  les  maladies  des  vers  a  soie,  t.  i.,'p.  70, 

1870. 

(5)  BLOCHMANN.     Quoted   by   L.   Pfeiffer  in  Die  Protozoen  als 

Krankheitserreger ;  1 89 1 . 

(6)  Janiscewski.     Munch,  med.  Wochenschrift,  1893. 

(7)  Bar  and  Renon.     Comptes  Rendus,  No.  23,  1895. 
Londe.     Comptes  Rendus,  No.  25,  1895. 

Nocard.     Un  nouveau  cas  de  tuberculose  congenitale.     Rev. 
de  Tuberculose,  No.  3,  1896. 

(8)  MAFFUCCI.     Centralbl.  f.  Bakt.  u.  Parasitenkunde,  Bd.  v.,  No. 

7  ;  and  Centralbl.  f.  allg.  Pathologie,  No.  1,  1894. 

(9)  Gartner.     Zeitschrift  f.  Hygiene,  Bd.  xiii. 

(10)  Jakh.      Virchow's  Archiv,  Bd.  cxlii.,  1895. 

(11)  Washbourne  and  others  in  the  discussion  on  latent  micro- 

organisms   at     the     Medico-Chirurgical    Society,   London. 
Lancet,  November,   1895. 

(12)  Stroganoff.     Centralbl./.  Gyndkologie,  No.  38,  1895. 

(13)  Sanarelli.     Centralbl.  f  Bakt.,  Bd.  x.,  1892. 

(14)  Hewlett.     Lancet,  June,  1895. 

(15)  Birch-Hirschfeld.     Zieglers  Beitr.  z.  path.  Anat.u.  allg. 

Path.,  Bd.  ix.,  1891. 

(16)  Wolff.     M.  Intemat.  Beitr.  z.  wissensch.  Med.     Festschr.  f. 

R.  Virchow,  Bd.  iii.,  1891. 

(17)  Wassermann.     Zeitschrift  f.  Hygiene,  Bd.  xvii.,  1894. 
KOSSEL,  H.     Zeitschrift f.  Hygiene,  Bd.  xxi.,  1895. 

(18)  Bernheim.     Erblichkeit  und    Ansteckung   der   Tuberculose. 

Mitteilungen  aus  dem  xi.  internat.  med.  Kongresse  in  Rom, 
1894.     Reference  in  Centralbl.  f  Bakt.,  No.  17,  1894. 


334  SCIENCE  PROGRESS. 

(19)  Honl.     Uber  kongenitale  Tuberkulose.    Reference  in  Centralbl. 

f.  Bakt.,  Bd.  xviii.,  1895. 

(20)  FREUNDand  Levy.  Berliner  klin.  Wochenschrift,No.  25,  1895. 

(21)  Neumann.     Archiv  f.  Kinderheilkunde,  Bd.  xiii. 

(22)  DUNGERN.     Centralbl.  f.  Bakt.,  Bd.  xiv.,  1893. 

(23)  Eberth.     Die  Tuberculose,  ihre  Verbreitung  und  Verhiitung, 

1 891. 

(24)  RlCKER.     Centralbl.  f.  allg.  Path.  v.  path.  Anat.,  Jan.,  1895. 

(25)  KOCKEL  and   LUNGWITZ.     Beitr.  z.  path.  Anat.   v.   allgem. 

Path.,  Bd.  xxi. 

George  A.   Buckmaster. 


Science  progress* 


No.  29.  July,   1896.  Vol.  V. 


PREHISTORIC  MAN    IN   THE  EASTERN 
MEDITERRANEAN. 

THE  purpose  of  these  notes  is  to  summarise  the  results 
of  recent  research  among  the  prehistoric  peoples  and 
civilisation  of  the  Eastern  Mediterranean  ;  especially  in  so 
far  as  these  prepare  the  environment  for  the  first  great 
civilisation  of  Europe,  namely,  that  of  Greece,  and  fill  the 
chronological  gap,  and  explain  such  communication  as 
existed,  between  this  and  the  equally  "  historic "  but  far 
earlier  civilisations  of  the  Euphrates  and  Nile  Valleys. 

A  strictly  "  Historic  "  Age  on  the  shores  of  the  ^gean 
Sea,  or  in  fact  in  the  Eastern  Mediterranean  at  all,  cannot 
be  said  to  begin  before  the  seventh  or  at  earliest  the  end  of 
the  eighth  century  B.C.  ;  and  everything  before  this  point 
would  certainly  have  been  classed  as  "  Prehistoric,"  but  for 
the  fact  that,  until  quite  lately,  the  preceding  centuries  have 
been  interpreted  wholly  in  the  light  of  a  voluminous  Greek 
tradition,  which  is  still  accepted  in  many  quarters  as 
fundamentally  historical  ;  though  now  with  wide  reserva- 
tions everywhere.  Consequently  prehistoric  archaeology 
and  ethnology  have  here  come  into  existence  as  accessory 
and  supplementary  studies,  and  the  data  of  the  literary 
tradition  have  been  used,  as  was  inevitable,  as  a  working 
hypothesis ;  which,  it  is  only  fair  to  say,  has  served  its  purpose 
fully  as  well  as  there  was  every  reason  to  expect.  Con- 
sequently again,  any  account  of  the  more  recent  and  more 

24 


336  SCIENCE  PROGRESS. 

strictly  anthropological  work  in  this  field  must  stand,  if  it  is 
to  be  intelligible,  in  close  relation  with  the  data  and 
assumptions,  which  have  so  mainly  determined  its  course. 

ANCIENT  TRADITIONS  AND   MODERN    INTERPRETATIONS. 

i.  The  data  upon  which  Greeks  of  the  sixth  and  early 
fifth  centuries  relied  for  the  reconstruction  of  their  own 
history  consisted  wholly  of  traditional  anecdotes,  appended 
to  traditional  genealogies,  or  grouped,  in  more  or  less  organic 
connection,  round  equally  traditional  events,  such  as  an 
invasion  of  the  Troad,  or  an  exploration  of  the  Euxine,  or 
the  adventures  of  a  typical  navigator  like  Odysseus.  Many 
of  the  lays  in  which  these  anecdotes  were  preserved  can  be 
traced  with  some  probability  to  their  places  of  origin,  which 
range  from  Cyprus  to  the  islands  off  the  west  coast  of 
Greece,  and  from  Thessaly  and  the  Troad  to  Crete.  All 
profess  to  represent  the  civilisation  of  the  yEgean  area  at  a 
period  removed  by  several  centuries  from  the  point  at 
which  the  Hellenic  world  emerges  into  history  ;  and  the 
traditional  chronology  of  historical  Hellas  went  up  to  an 
era  which  is  slightly  later,  but  approximately  contemporary 
with  the  latest  episodes  of  the  Epic  poems.  Now  though  the 
lays  which  display  the  greater  literary  skill  and  the  maturer 
idiom  give  a  less  vivid  and  more  conventional  picture  ;  and 
though  occasional  allusions  occur  to  customs  and  beliefs 
which  are  characteristic  of  Hellenic  culture,  those  others 
which  Greek  tradition  reckons  primary,  namely,  the  Iliad 
and  the  Odyssey,  are  obviously  at  close  quarters  with  their 
subject ;  and  if  there  is  one  thing  certain  about  the  civilisa- 
tion of  the  "Homeric  Age"  thus  described,  it  is  that  it 
differs  in  nearly  every  important  feature  from  that  of  the 
"  Hellenic  Age"  of  historical  Greece. 

2.  The  Greeks,  in  fact,  themselves  regarded  their  earliest 
literature  as  antedating  the  chronological  limits  of  their 
history,  and  already  perceived  that  they  belonged  to  a 
different  order  of  things.  In  particular,  the  ethnography 
of  the  /Egean,  preserved  in  an  admittedly  late  and  de- 
generate lay,  differs  uniformly  from  that  of  historic  Hellas  as 
far  back  as   it  can  be  traced,  and  those   names  are  almost 


PREHISTORIC  MAN,  ETC.  337 

absent  by  which  the  Greek  race  was  denoted  historically  ; 
by  its  western  neighbours  as  "EAXiji'tc,  by  its  eastern  neigh- 
bours as  'laoveg  (Javan).  This  inconsistency  was  attributed 
by  the  Greeks  themselves  to  a  period  of  invasion  and 
migration  analogous  to  that  which  broke  up  the  Graeco- 
Roman  civilisation  of  the  Mediterranean.  Dorian, 
Thessalian  and  Boeotian  mountaineers  were  represented  as 
forcing  the  barrier,  or  descending  from  the  highlands,  of  the 
Balkans,  bringing  the  old  established  "  Achaean  "  civilisa- 
tion to  an  abrupt  close,  and  reducing  the  /Egean,  and 
mainland  Greece  in  particular,  to  a  chaotic  and  barbarous 
state,  the  recovery  from  which  is  the  dawn  of  the  historical 
Hellenic  genius. 

3.  Some  facts  within  their  own  experience  went  to 
confirm  this  view.  Here  and  there  tribes  retained  the  names 
and  the  mode  of  life  of  the  earlier  age  ;  or  a  noble  family 
professed  to  trace  its  descent  beyond  the  limits  of  current 
genealogy,  and  to  identify  itself  with  a  Royal  house  of 
Achaean  princes ;  and  here  and  there  ruined  fortresses 
remained,  or  ancient  tombs  had  been  disturbed,  which 
seemed  to  confirm  the  description  of  Achaean  splendour  in 
the  ballads. 

4.  Thus  much  had  been  established  from  the  beginning 
of  Greek  History  onwards,  and  had  not  been  seriously 
shaken  by  successive  attempts  to  discredit  the  traditional 
view.  The  theories  that  the  lays  are  comparatively  late 
compositions,  and  that  they  stand  in  no  close  relation  to 
a  pre- Hellenic  age  ;  that  the  Achaean  Age  is  an  invention, 
and  the  Period  of  the  Migrations  a  hypothesis  to  explain  its 
inconsistency  with  the  facts  of  historical  geography,  all 
prove  too  much,  and  may  be  met  with  argument  a  ad 
hominem  from  the  same  traditional  data.  No  literary 
critic  of  the  Epic  has  yet  purged  himself  of  a  sediment  of 
traditional  preconception ;  and,  in  proportion  as  one  or 
another  has  attempted  to  do  so,  he  has  been  reduced  to  a 
merely  agnostic  position. 

5.  Further,  until  very  recent  years,  every  attempt  which 
was  made  to  elucidate  the  civilisation  of  the  Homeric  Age 
by  the  monuments  of  early  Greek  civilisation  rested  upon 


338  SCIENCE  PROGRESS. 

the  assumption  that  the  representations  of  dress,  armour, 
etc.,  of  the  sixth,  fifth  and  fourth  centuries  B.C.,  were  valid 
illustrations  of  poems  which  at  the  latest  belonged  to  the 
seventh,  and  on  an  average  were  assigned  to  the  ninth  or 
tenth  century.  The  reason  of  this  was  that  Homeric  sub- 
jects in  Greek  art  are  uniformly  furnished  with  accessories 
of  the  age  of  the  artist,  and  that  until  the  study  of  Classical 
Antiquities  began  to  be  infected  with  the  "  evolutionary 
notions  "  which  had  already  long  been  current  in  all  other 
departments  of  Ethnography,  the  attention  of  students  of 
Greek  art  and  culture  was  strictly  confined  to  mature  and 
decadent  art ;  everything  which  could  not  be  assigned  to  a 
century  subsequent  to  the  fifth  was  either  dismissed  as 
barbaric,  or  discounted  as  a  "  Phoenician  importation  "  ;  the 
part  which  "  Phoenician  "  fables,  ancient  and  modern,  have 
played  in  the  historical  study  of  the  Mediterranean  area  will 
be  considered  briefly  later  on.  Such,  for  example,  was  the 
received  opinion — so  far  as  there  was  one — of  such  dis- 
coveries of  pre-Hellenic  culture  as  those  of  M.  Fouque's 
expedition  to  the  Island  of  Santorin  (Thera,  1862),  where,  in 
the  course  of  a  geological  investigation,  a  primitive  settle- 
ment was  found  under  a  thick  bed  of  volcanic  debris,  or  of 
those  of  MM.  Salzmann  and  Biliotti  (1868-71),  who  in 
searching  for  antiquities  in  Rhodes  found  at  Ialysos,  for  the 
British  Museum,  a  magnificent  collection  of  early  vases 
which  are  now  known  to  be  Mykenaean,  and  second  only  in 
quality  and  variety  to  those  from  Mykense  itself.  The 
Santorin  settlement  was  simply  taken  to  confirm  the  legend 
of  the  Phoenician  colony  of  Kadmos  (Hdt.  iv.,  147),  and 
the  vases  from  Ialysos  were  explained  as  the  barbarous  but 
immediate  predecessors  of  those  from  Kamiros,  were  classed 
with  them  as  "  Grseco-Phcenician,"  and  were  referred  to  the 
seventh  century,  in  spite  of  the  absence  of  Egyptian  objects 
of  the  twenty-sixth  Dynasty,  and  the  presence  of  objects  of 
the  eighteenth  :  a  view  which  in  certain  quarters  is  not 
yet  quite  extinct. 

6.  It  was  not  till  1871  that  Dr.  Heinrich  Schliemann 
was  enabled  to  execute  his  lifelong  ambition  of  testing  with 
the  spade  the  Greek  tradition  that  the  site  of  the  Grseco- 


PREHISTORIC  MAN,  ETC.  339 

Roman  town  of  Ilion  was  also  the  site  of  Homer's  Troy. 
The  tradition  had  indeed  been  sorely  handled  by  Deme- 
trios  of  Skepsis,  a  local  antiquary  of  the  second  century 
B.C.,  on  the  geological  ground  that  the  Plain  of  Troy  is  of 
recent  alluvial  formation  ;  and  by  other  critics  on  the  score 
of  inconsistency  with  the  Homeric  narrative.  But  the  Bali 
Dagh,  the  site  suggested  by  Demetrios,  and  in  fact  the 
only  alternative,  is  far  more  inconsistent,  and  is  put 
absolutely  out  of  question  by  Dr.  Schliemann's  discoveries. 
In  successive  seasons  (1S71-3,  1876-82)  he  laid  bare  not 
one,  but  six  cities,  built  one  after  another  on  the  same  site, 
and  forming  an  accumulation  of  walls  and  debris  some 
thirty  feet  deep  ;  and,  among  these,  two  additional  layers 
have  been  distinguished  in  the  confirmatory  excavations  of 
Dr.  Dorpfeld,  1892-94.  The  latter,  however,  indicate  that 
Dr.  Schliemann's  earlier  work  was  not,  from  the  circum- 
stances of  the  case,  sufficiently  closely  watched  throughout, 
and  that  in  some  cases  objects  were  probably  picked  up  at 
lower  levels  than  those  to  which  they  properly  belong.  In 
particular,  it  is  not  clear  that  the  cache  of  jewellery  and 
plate  known  as  the  "Great  Treasure  of  Priam"  was  not 
hidden  originally  in  a  shaft  of  some  depth. 

7.  Dr.  Schliemann  claimed  as  the  Homeric  Troy  the 
Second  Town  from  the  bottom,  which  had  perished  by  fire, 
and  in  which  the  "  Great  Treasure  "  was  found.  But  the 
Sixth  Town,  which  Dr.  Schliemann  described  as  Lydian, 
was  shown  by  Dr.  Dorpfeld  in  1892-93  to  be  larger  and 
more  important  than  was  at  first  supposed,  and  to  cor- 
respond closely  with  the  remains  found  subsequently  at 
Mykenae  and  elsewhere. 

8.  With  the  same  purpose  in  view  of  testing  the 
Homeric  tradition,  Dr.  Schliemann  proceeded  in  1875-6  to 
excavate  the  citadel  of  Mykenae,  in  the  Peloponnese,  the 
traditional  centre  of  the  Achaian  feudal  confederacy.  Here 
the  results  were  equally  unexpected,  but  no  less  confirma- 
tory of  the  legend.  A  civilisation  was  brought  to  light 
wholly  un- Hellenic,  but  far  from  barbarous ;  greatly  in 
advance  of  all  but  the  latest  layers  of  Hissarlik,  and 
presenting  already  the  marks  of  decadence  after  a  protracted 


34o  SCIENCE  PROGRESS. 

career.     The   pottery,  the   personal  ornaments,  and  in  fact 
the   whole  cycle   of  the  art,   were    at   once   recognised  as 
identical    with    those    of    Ialysos,    while    the    stone-fenced 
burial-place  discovered  just  within  the  "  Lion  Gate"  of  the 
citadel,    with    its   six    "  shaft    graves "   and  their   enormous 
wealth  of  gold  vessels   and  ornaments,   seemed  ample  con- 
firmation of  the  legendary  wealth   of  "  golden    Mykenae," 
and  was  proclaimed,  in  the  first  enthusiasm  of  the  discovery, 
as    the    tomb    of  Agamemnon    himself.     The    further    re- 
searches which  have  been  made  almost  continuously  from 
1886  onwards   by   M.    Tsountas  for    the    Greek    Archaeo- 
logical Society  have   confirmed  in  all   essential   points  the 
first  general  impression,  but  the  discovery  of  later  tombs  in 
the  lower  quarters  of  the  town  has  made  it  possible  to  trace 
an  order  of  progress  and  to  extend  the  limits  of  the  period. 
9.   Subsequent  excavations  at  Tiryns  and  Orchomenos 
by   Dr.    Schliemann,    and    on    a  number  of  other  sites  in 
Greece  and  the    yEgean    Islands   by   the   Greek   Archaeo- 
logical Society  and  the  foreign   Institutes  in  Athens,  have 
demonstrated  that  this  civilisation,  which  has  acquired  the 
provisional  name   of  Mykenaean,  is   widely  represented  in 
the  yEgean  area  and   especially  in   its  southern   part  ;  that 
its    influence    extended    over    the    Central    and     Eastern 
Mediterranean  from  Sicily  to  Cyprus;   that  it  penetrated, 
intermittently  at  all  events,   into   Egypt,   where  its  appari- 
tion can  be  approximately  dated,   and  whence  it  imported 
much,  and  borrowed  somewhat,  but  without  losing  its  own 
individuality  ;   and,  most  striking  of  all,  that,  after  a  long 
period   of   apparently  continuous   maturity,   it   falls   into    a 
sudden  decadence  ;  leaving,  to  all  appearance,  just  the  same 
gap  between  itself  and    the  first   traces  of    Hellenic  Art, 
as   we    have  noted  already,   on  the  literary  side,  between 
the    Homeric    Age   and    the  beginning    of   Hellenic   His- 
tory.      It  should  be  further  noted,    however,   that  in    the 
last  few  years  many  facts  have  come  to  light,  especially  in 
Attica,  in  Crete,  and,  most  of  all,  in  Cyprus,  which  seem  to 
indicate  how  that  gap  may  eventually  be  filled.      It  is  from 
the   pottery,    almost    without    exception,    that    the   leading 
indications  have  been  derived.      Fragments  of  baked  clay 


PREHISTORIC  MAN,  ETC.  341 

are  practically  indestructible,  even  though  the  vessels  which 
they  composed  have  been  shattered.  Moreover,  all  the 
unrefined  varieties  of  clay,  and  many  even  of  the  best 
levigated,  present  features  by  which  their  place  of  origin 
may  be  recognised.  Consequently,  in  this  material, 
modelling  and  decoration  can  be  perpetuated  as  in  no  other 
way  ;  and,  what  is  more  important,  the  intrinsic  worthless- 
ness  of  earthenware  has  often  preserved  it  from  the  dis- 
placement and  destruction  which  almost  inevitably  overtake 
objects  of  gold,  bronze,  and  marble.  The  resulting  pre- 
ponderance of  ceramographic  references  in  the  bibliography 
which  follows  these  notes  must  therefore  be  taken  as 
indicating  the  character  of  the  evidence  which  is  most 
accessible,  and  of  the  method  which  has  actually  proved 
most  fruitful  :  not  that  the  pottery  really  took  so  large  a 
place  in  primitive  art  as  might  be  inferred  from  its  actual 
abundance,  and  its  scientific  importance. 

10.  Consequently  the  study  of  Early  Man  in  the  JEgean 
has  entered  within  a  few  years  on  a  new  phase,  and  pre- 
sents the  following  problems:  (1)  To  reconstruct  in  detail 
the  history  of  the  Mykenaean  civilisation ;  its  origin,  its  charac- 
ter, range  and  influence,  and  its  decline  ;  (2)  to  investigate  the 
causes  of  that  relapse  into  barbarism,  which  both  literature 
and  archaeology  attest ;  (3)  to  determine  the  ethnological 
position  of  the  race,  or  races,  who  originated,  maintained, 
and  overthrew  it,  and  their  relationship  with  the  historic 
inhabitants  of  the  same  area  ;  and  (4)  as  a  special  study,  to 
determine  the  relation  in  which  the  Hellenic  traditions  of 
the  Achaean  Age,  and  the  lays  in  which  they  were  preserved, 
stand  to  the  civilisation  which  they  certainly  seem  to  com- 
memorate, and  which  owes  its  discovery  simply  to  the 
application  to  them  of  a  new  method  of  criticism. 

(1)    THE    FIRST    KNOWN    CULTURE    OF    THE    EASTERN 

MEDITERRANEAN. 

1 1.  Palaeolithic  Man  seems  to  have  left  no  traces  in  the 
Levant  comparable  with  those  in  North  Europe,  or  with 
the  plateau  and  upper-gravel  flints  of  the  Nile  Valley.  But 
the  scarcity  of  evidence  is  partly  due  to  the  indifference  of 


342  SCIENCE  PROGRESS. 

the  natives  to  such  objects,  and  to  the  almost  complete 
diversion  of  trained  research  into  more  obvious  and  attrac- 
tive departments  ;  partly  also  to  the  comparative  rarity, 
except  in  Egypt,  both  of  workable  flints  and  of  the  high- 
level  gravels  in  which  they  are  usually  preserved.  From 
Greece  itself  only  one  palaeolithic  implement  is  recorded 
hitherto  ;  a  flint  celt  from  Megalopolis  in  Arkadia  (Rev. 
Arch.,  xv.,  1 6  ff). 

12.  Neolithic  Man,  however,  can  be  traced  over  the 
whole  area.  Masses  of  hard  crystalline  rock  are  frequent 
and  accessible,  and  furnished  implements  of  characteristic 
types ;  short  full-bodied  celts,  more  or  less  markedly 
conical  behind,  and  ground  to  a  rather  obtuse  edge.  Ob- 
sidian was  largely  exported  from  Melos  and  Thera  to  the 
neighbouring  islands,  and  to  the  mainland  of  Greece,  and 
was  worked  up  at  Korinth  and  on  several  sites  in  Attica. 
Jade  of  good  quality  was  sent  from  Asia  Minor  outwards 
across  the  yEgean  ;  but  it  is  not  yet  clear  whether  the 
source  of  the  common  green  variety  is  in  Asia  Minor  itself 
or  further  east :  the  jade  implements  become  commoner 
eastwards,  and  the  finest  collection  from  anysingle  neighbour- 
hood is  that  brought  by  Mr.  D.  G.  Hogarth  in  1894  from 
Aintab  in  N.  Syria  (Ashm.  Mus.,  Oxford). 

13.  Tombs  of  this  stage  of  culture  have  not  been  found 
— or  sought — in  sufficient  numbers  to  justify  discussion  or 
to  contribute  any  facts  of  importance.  The  necropolis  of 
Psemmetismeno  in  Cyprus,  for  example,  contains  besides 
typical  early  Bronze  Age  tombs  a  still  more  primitive  class, 
in  which  the  pottery  is  exceedingly  rude,  and  the  charac- 
teristic red-polished  ware  of  the  early  Bronze  Age  is 
wanting  ;  but  though  bronze  is  absent,  no  stone  implements 
are  present.  On  the  other  hand  the  few  tombs  recorded 
as  containing  stone  implements  are  brought  down  by  their 
general  character  well  within  the  Bronze  Age. 

14.  Exception  must  however  be  made  in  favour  of  the 
Nile  Valley,  for  Professor  Flinders  Petrie  in  1895  found, 
at  Ballas  and  Nagada,  both  tombs  and  villages  of  an 
invading  race,  apparently  Libyan,  which  had  brought  the 
art  of  flint  working  to  unequalled  proficiency,  and  remained 


PREHISTORIC  MAN,  ETC.  343 

almost  ignorant  of  the  copper  which  was  already  in  fairly- 
common  use  under  the  Sixth  Dynasty,  which  immediately 
preceded  their  irruption  into  Egypt.  But  the  significance 
of  this  discovery  and  of  our  very  limited  knowledge  of  the 
Libyan  people  and  their  civilisation  will  be  better  discussed 
at  a  later  stage. 

15.  On  the  other  hand,  several  Settlements  of  the 
Neolithic  Age  have  been  examined.  Typical  is  the  lowest 
town  of  Hissarlik,  though  it  has  actually  yielded  a  few 
simple  copper  weapons.  The  implements  are  of  local  flint 
and  imported  obsidian,  of  green-stone  and  allied  rocks  from 
the  interior  of  the  Troad,  and  of  jade  ;  some  of  the  common 
green  Anatolian,  others  of  finer  yellowish  kinds  {cf.  the 
specimen  in  Ashm.  Mus.  attributed  to  Melos),  and  one 
small  celt  of  the  pure  white  variety  which  is  not  known 
to  exist  native  except  in  China. 

16.  The  fortifications  and  house  walls  of  the  "First  City" 
are  of  very  rough  unhewn  rubble  ;  its  pottery  is  of  local 
fabric,  made  wholly  without  the  use  of  the  potter's  wheel, 
and  almost  uniformly  tinted  black  by  a  carbonaceous  pig- 
ment, intentionally  applied  and  accentuated  in  the  burning  ; 
many  of  the  forms  are  closely  allied  to  those  of  the  neolithic 
and  early  bronze  ages  in  Central  Europe,  and  of  the  corre- 
sponding deposits  of  Greece  and  Cyprus.  This  lowest 
settlement  is  separated  from  the  rest  by  a  layer  of  natural 
soil,  which  represents  an  interval  during  which  the  site  lay 
desolate  ;  it  is  therefore  distinctly  older  than  the  succeeding 
cities.  But  the  advanced  and  special  technique  of  the 
Pottery  of  the  First  City,  and  the  fact  that,  on  Schliemann's 
authority,  copper  implements  already  occur,  indicate  the  end 
rather  than  the  beginning  of  the  Neolithic  stage  ;  and  the 
Neolithic  evidence  from  elsewhere  is  best  summarised  here, 
before  going  further  in  the  series  at  Hissarlik. 

17.  Settlements  of  similar  character,  but  each  with  its 
own  local  peculiarities,  occur  (r)  on  an  unexcavated  site, 
commanding  the  Bosphorus  as  Hissarlik  commands  the 
Dardanelles.  (2)  On  the  "  Kastri "  near  Achmet-aga  in 
Eubcea,  a  low  hill  fortified  with  earthworks  and  approached 
by  a  hollow  way,  like  the  hill  camps  of  the  south  of  England. 


344  SCIENCE  PROGRESS. 

(3)  Beside  Dombrena  near  Thebes  in  Central  Greece  :  the 
site  has  not  been  described,  but  neolithic  implements  are 
very  frequent :  among  them  is  a  potter's  burnisher  of  white 
quartzite  (Finlay  Coll.,  280.  Athens).  (4)  On  the  Acro- 
polis of  Athens  many  implements  and  vases  were  entirely 
confused  by  the  levelling  of  the  summit  in  the  fifth  century 
B.C.  ;  on  the  south  side  (in  the  space  afterwards  known  as 
the  UtXapyiKov)  is  a  layer  of  neolithic  pottery  with  obsidian 
flakes  and  a  potter's  burnisher,  almost  wholly  destroyed 
by  the  recent  excavations,  and  only  preserved  where  it  is 
left  to  support  the  fragmentary  walls  of  the  Mykenaean 
settlement.  The  material  of  the  pottery  is  Ilissos  mud, 
not  the  Kerameikos  clay  of  the  Kephissos  valley.  (5) 
Beyond  the  Ilissos,  between  Hymettos  and  the  sea,  the 
exact  site  is  unknown,  potsherds  are  common  on  the  surface. 
The  many  stone  heaps  in  this  district  seem  to  have  been 
accumulated  from  off  the  fields  on  to  barren  spots  ;  two, 
opened  south-east  of  Kara  in  1895,  were  quite  barren;  a 
tumulus  north-east  of  Kara,  surreptitiously  opened,  con- 
tained a  Mykenaean  interment  (Ashm.  Mus.).  (6)  Primitive 
pottery  is  common  on  the  west  end  of  the  cliff  which  runs 
along  the  coast  from  New  Corinth  nearly  to  the  site  of 
Lechaion. 

18.  The  "Second  City"  of  Hissarlik  has  marked  points  of 
similarity  with  the  first,  but  represents  a  decided  advance, 
and  has  notable  characteristics  of  its  own.  The  walls,  great 
and  small,  are  of  better  masonry  below,  and  of  sun-dried 
brick  above,  with  bonding  courses  and  terminal  uprights 
(antae)  of  timber  ;  the  centre  of  the  fortress  is  occupied  by  a 
"  chief's  house,"  consisting  of  three  oblong  buildings  with 
portico  entrances  at  one  end  in  a  courtyard  entered  by  a 
covered  gateway.  The  pottery  is  still  of  unlevigated  clay, 
and  mostly  hand-made  ;  it  is  no  longer  blackened  as  before, 
but  either  left  as  it  is,  or  covered  with  a  red  slip,  which  con- 
tinues to  occur  in  the  layers  above  ;  new  and  characteristic 
forms  appear,  some  peculiar,  others  again  common  to 
Central  Europe,  to  the  Greek  islands  or  to  Cyprus. 
Stone  implements  are  still  in  common  use,  but  copper  and 
bronze  begin  to  be  frequent  though  they  are  still  of  simple 


PREHISTORIC  MAN,  ETC.  345 

types.  But  the  pre-eminent  feature  of  the  Second  Town  is 
the  discovery  of  more  than  one  buried  "  Treasure  "  of  gold 
and  silver  jewellery  and  vessels,  the  latter  certainly  of 
local  manufacture,  for  the  forms  closely  correspond  with 
characteristic  types  of  the  pottery. 

19.  The  Second  Town  perished  in  a  general  conflagra- 
tion, and  the  Third,  Fourth  and  Fifth  Towns  above  it 
never  attained  to  anything  like  its  magnificence.  They 
mark,  however,  a  gradual  advance  of  civilisation  and  form  a 
transition,  more  and  more  rapid  as  it  proceeds,  towards  the 
Sixth  Town,  a  quite  distinct  and  well-marked  settlement  of 
"  Mykenaean "  invaders,  in  which  imported  pottery,  and 
native  imitations  of  this,  occur  alongside  of  fully  developed 
indigenous  forms,  which  again  recall  in  characteristic  details 
many  Central  European  types.  This  Sixth  Town  is  the 
only  one  which  can  be  even  approximately  dated  chrono- 
logically ;  it  is  certainly  prior  to  1000  B.C.,  and  need  not  be 
later  than  1 300  ;  the  Fifth  and  lower  settlements  must  of 
course  necessarily  be  older  than  this. 

20.  It  has  been  already  hinted  that  the  "  Treasure  of 
Priam  "  may  belong  to  a  period  somewhat  later  than  the 
Second  Town,  though  not  so  late  as  the  sixth  or 
"  Mykenaean "  Town.  Whether  this  be  so  or  not,  we 
have  in  the  jewellery  an  early  example,  perhaps  a  prototype, 
of  the  characteristic  gold  work  of  the  Mykenaean  Age  ; 
but  if  the  "  Treasure  "  is  contemporary  with  the  layer  in 
which  it  was  found,  the  time  limit  for  the  whole  series  at 
Hissarlik  must  probably  be  contracted  downwards.  In 
any  case  we  must  believe  that  the  earliest  civilisation  of 
Hissarlik  was  not  so  wholly  barbarous  as  appears  at  first 
sight. 

21.  Imported  objects  found  at  Hissarlik  indicate  a  wide 
range  of  foreign  connections.  The  fragments  of  porcelain 
point  to  Egypt  ;  the  lapis  lazuli  axe  from  a  neighbouring 
site,  to  Turkestan  ;  the  silver  vases  probably  to  the  eastern 
half  of  Asia  Minor  ;  the  types  of  the  bronze  implements 
alike  to  Cyprus  and  to  the  Danube  Valley  ;  and  the  amber 
to  the  shores  of  the  Baltic.  This  wide  commerce  does  not, 
of  course,  imply  direct  intercourse,  but,  from  its  geographical 


346  SCIENCE  PROGRESS. 

position  on  the  Hellespont,  Hissarlik  must  have  been  a 
point  of  convergence  for  any  trade  between  the  East  and 
Europe,  and  the  catalogue  of  the  allies  of  the  Trojans  in  Iliad 
II.,  though  it  refers  to  a  later  period,  ranges  them  (i)  up 
the  Hebros  Valley  into  the  Balkans,  and  along  (2)  the 
North  and  (3)  the  West  coast  of  Asia  Minor;  i.e.,  along 
three  well-known  routes  of  early  trade. 

22.  The  metallic  objects  of  Hissarlik  are  of  particular 
value  as  links  between  two  principal  copper-working  areas, 
Cyprus  and  Central  Europe.  The  latter  really  falls 
beyond  our  present  view,  but  must  be  noted — mainly  to  be 
rejected — as  a  possible  source  of  the  early  Mediterranean 
Bronze. 

23.  The  use  of  copper  in  Cyprus  goes  back  far  beyond 
the  point  where  it  can  be  dated  with  any  certainty,  and 
everything  goes  to  show  that,  while  southwards,  namely, 
in  Egypt  under  the  Fourth  Dynasty,  Cypriote  types  appear 
from  the  first  side  by  side  with  others  which  are 
probably  Sinaitic,  northward  the  same  types  extend,  past 
Hissarlik,  into  the  Danube  Valley,  and  are  imitated  and 
amplified  into  derivative  forms  throughout  Central  Europe  ; 
returning,  almost  unrecognisable,  into  the  Mediterranean 
area  in  the  series  from  Spain,  which  is  clearly  not  directly 
derivative,  and  may  be  of  comparatively  late  origin. 

24.  The  obvious  suggestion  that  Central  Europe  may 
have  worked  copper  independently  is  met  (1)  by  the  com- 
parison of  the  secondary  forms, — e.g.,  only  in  Cyprus  can  the 
actual  synthesis  of  double-bladed  axe  heads,  by  welding 
two  simple  ones,  be  observed  ;  (2)  by  the  fact  that,  along 
with  the  characteristic  and  indigenous  metallurgy,  the 
ceramic  technique  of  Cyprus,  with  red  hand-polished  sur- 
face and  incised  ornament  filled  with  white  earth,  can  be 
traced  across  Asia  Minor  and  into  South-eastern  Europe  ; 
the  red  slip  as  far  as  Brus  in  Transylvania  ;  the  ornament 
into  the  Mondsee  of  Lower  Austria,  and  the  pile-dwellings 
of  Switzerland,  becoming  ever  more  mongrel  and  degenerate 
as  it  proceeds. 

25.  It  is  important  to  note  that  at  Hissarlik  a  return 
current  is  already  evident  ;  the  pottery  and  the  metal  im- 


PREHISTORIC  MAN,  ETC.  347 

plements  reproduce  European  types  as  well  as  Cypriote, 
and  this  is  confirmed,  not  only  by  traditional  and 
ethnological  considerations,  but  also  by  the  occurrence, 
somewhat  later,  in  the  yEgean  area,  not  only  of  frequent 
amber,  but  of  characteristically  Danubian  types  of  bronze 
implements. 

26.  The  Bronze  Age  civilisation  of  Cyprus  is,  thanks  to 
repeated  researches,  far  more  continuously  and  completely 
known  than  any  other  part  of  the  area.  It  was  undoubtedly 
of  very  long  duration,  and  certainly  follows  that  of  the 
Stone  Age  without  change  or  break ;  and  it  is  no  exaggera- 
tion to  say  that,  until  a  period  between  the  twelfth  and  the 
eighteenth  Egyptian  Dynasty,  Cyprus  was  in  all  essential 
respects  in  advance,  not  only  of  the  coasts  of  Asia  Minor 
and  the  /Egean,  but  even  of  the  coast  of  Syria  and 
Palestine. 

27.  All  the  earliest  weapons,  whether  in  Cyprus  or 
elsewhere,  in  Egypt,  or  the  Levant,  are  of  almost  pure 
copper.  Tempering  is  effected,  not  by  alloying  with  zinc  or 
tin,  or,  as  in  the  Caucasus,  with  antimony  from  the  natural 
double-sulphide  ore,  but  by  "  under-poling  "  the  copper  so 
as  to  leave  it  hard  and  even  brittle  from  the  presence  of 
copper  oxide.  The  same  applies  to  the  Egyptian  copper 
weapons  of  the  fourth,  fifth,  and  even  sixth  Dynasty  ;  but 
Egypt,  though  later  on  it  has  important  connections  with 
Cyprus,  obtained  its  first  copper  from  the  mines  of  Sinai, 
and  has  a  set  of  typical  forms  peculiar  to  itself.  Cyprus, 
however,  supplied  the  Syrian  coast  with  copper  weapons 
down  at  all  events  to  the  time  of  the  eighteenth  Dynasty. 
Stone  implements  are  very  rarely  found  in  Cyprus, 
and  it  is  possible  that  either  the  island  was  not  reached 
much  before  the  beginning  of  the  Bronze  Age,  or  that  its 
wealth  of  copper  was  discovered  at  once,  and  superseded 
the  stone  age  prematurely.  In  its  earlier  stages  metallic 
implements  are  rare,  and  the  pottery — always  made  by 
hand — is  covered  with  a  bright  red  glaze  which  was  polished 
with  a  stone  or  bone  rubber  (horse  teeth  were  commonly 
used),  and  ornamented,  if  at  all,  either  by  incised  lines  or 
by  pellets  of  clay  rudely  modelled  after  plants,  snakes  and 


348  SCIENCE  PROGRESS. 

horned  animals.  In  its  earlier  part,  therefore,  the  civilisa- 
tion, so  far  as  it  is  known,  is  peculiarly  uniform  in  character, 
and  displays  no  trace  of  foreign  influence  ;  except  only  that 
the  characteristic  red-polished  glaze  of  the  pottery,  already 
mentioned,  is  almost  identical  with  that  of  the  Neolithic 
Libyan  people  of  Ballas-Nagada,  and  of  their  "  Amorite  " 
kinsfolk  in  South  Palestine.  Even  here,  however,  there  is 
no  evidence  at  present  of  imitation  on  either  side.  The 
strong  influence  which  Cyprus  exercised,  through  its  copper 
trade,  over  the  neighbouring  coastland  is  best  illustrated 
by  the  discoveries  of  Dr.  Bliss  at  Tell-el-Hesy,  on  the 
coast  plain  of  Palestine  (Philistia),  some  sixteen  miles  from 
Gaza.  The  site  consists  of  an  acropolis  with  eight  "Cities  " 
superimposed  as  at  Hissarlik.  The  mass  of  the  remains 
represent  an  indigenous  "Amorite"  civilisation  of  low  type, 
related,  according  to  Professor  Flinders  Petrie,  to  that 
of  the  Libyan  invaders  of  Ballas-Nagada.  But  bronze  appears 
from  the  bottom  of  the  series  upwards,  and  iron  already  in 
City  Four,  which  with  City  Three  appears  to  be  contemporary 
with  the  eighteenth  Dynasty  and  the  Mykenaean  Age. 
The  bronze  types  are  derivative,  partly  from  Cyprus,  partly 
from  Egypt  ;  and  Cypriote  importations  of  the  later  painted 
fabrics  occur  in  Cities  Two  and  Three  together  with  native 
imitations.  The  red-polished  pot  fabric  of  Tell-el-Hesy, 
however,  belongs  to  the  Amorite  civilisation,  and  is  not 
necessarily  borrowed  from  that  of  Cyprus. 

28.  In  the  latter  half  of  the  Bronze  Age,  Cyprus  with 
characteristic  conservatism  fell  for  a  while  slightly  behind 
its  neighbours,  and  began  to  import  ornaments  and  articles 
of  luxury  from  Egypt  and  the  Syrian  and  Cilician  coasts. 
In  this  stage  the  red-polished  ware  tends  to  deteriorate  in 
colour  and  finish  ;  the  bronze  weapons  become  more 
numerous,  and  contain  a  higher  percentage  of  tin,  and 
occasionally  jewellery  of  coarse  silver-lead,  all  of  native  make, 
is  found  in  the  more  richly  furnished  tombs.  Babylonian 
cylinders  occur  rarely  as  imports,  with  a  multitude  of  charac- 
teristic native  cylinders.  Egyptian  scarabs  and  porcelain 
beads  are  also  found  rarely  ;  and  with  these  again  a  very 
common  variety  of  coarse  crumbly  porcelain   badly  glazed 


PREHISTORIC  MAN,  ETC.  349 

with  a  very  faint  blue  :  the  pigment  was  evidently  difficult  to 
obtain,  and  was  used  but  sparingly  by  the  native  artist. 
But  meanwhile  the  discovery  of  the  art  of  ornamenting  the 
natural  surface  of  clay  vessels  with  an  encaustic  umber  pig- 
ment, wherever  it  may  have  originated,  seems  to  appear 
in  Cyprus  (where  umber  is  extensively  worked)  at  least 
as  early  as  anywhere  else  ;  first  in  company  with,  but  later 
almost  wholly  superseding,  the  older  mode  of  incising  linear 
ornaments  on  a  prepared  and  polished  surface. 

29.  The  simply  painted  pottery  is  followed,  though  not 
immediately,  by  several  other  fabrics  which,  though  probably 
native  to  Cyprus,  are  represented  in  some  quantity  on 
Egyptian  sites  of  the  twelfth  Dynasty  and  later  dates,  and 
also  in  equivalent  layers  in  the  stratified  mound  of  Tell-el- 
Hesy,  in  the  "Hittite"  Sinjirli,  and  sporadically  else- 
where ;  one  very  characteristic  variety,  with  dark  body, 
white  chalky  slip,  and  black  almost  glossy  paint,  has  been 
found  even  so  far  afield  as  the  Island  of  Thera,  the  Acro- 
polis of  Athens,  and  the  "  Sixth  City"  of  Hissarlik. 

30.  The  specimen  from  Thera  was  found  in  company 
with  vases  of  a  distinct  and  local  style  ;  some  still  with 
coloured  surface  and  incised  ornament,  others  with  simple 
painted  patterns.  The  forms,  however,  and  the  whole 
fabric,  are  quite  distinct  from  those  of  Cyprus,  and  show  a 
graceful  freedom  which  is  quite  new;  though  they  are  clearly 
derivative  from  a  ceramic  of  the  Hissarlik  type.  Most 
important  of  all,  the  wholly  geometrical  and  mainly  linear 
ornament  which  has  been  hitherto  universal  is  combined 
with  or  replaced  by  a  thoroughly  and  vigorously  natural- 
istic study  of  animal  and  vegetable  forms,  and,  in  combina- 
tion with  the  latter,  spiral  motives  appear,  hitherto  unknown 
but  destined  to  a  long  and  eventful  career.  These  naturalistic 
and  curvilineardesigns  are  notonlyrepresentedon  the  pottery, 
but  are  also  frescoed  upon  the  plastered  walls  of  the  houses  ; 
they  may  consequently  be  taken  to  be  locally  characteristic. 
The  settlement  at  Thera  was  found  beneath  a  thick  bed  of 
volcanic  debris,  and  had  evidently  been  suddenly  abandoned  ; 
metallic  objects  are  rare,  but  this  may  well  be  due,  as  M. 
Tsountas  suggests,  to  the  flight  of  the  inhabitants — for  no 


350  SCIENCE  PROGRESS. 

skeletons  were  found  ;  and  a  few  copper  implements  and 
gold  ornaments  remained  to  confirm  the  inference  from  the 
pottery  as  to  its  position  in  the  series. 

31.  Settlements  and  tombs  of  the  same  character  have 
since  been  noted  in  many  islands  of  the  Archipelago,  especi- 
ally in  Syros,  Melos,  Antiparos  and  Amorgos  ;  and  this 
"  Cycladic  "  type  of  ornament  and  general  civilisation  is  not 
only  closely  paralleled  by  the  earliest  remains  at  Mykense, 
Tiryns,  Athens  and  elsewhere,  but  is  connected  by  an 
almost  continuous  series  with  the  fully  developed  art  and 
civilisation  of  the  Mykensean  Age  itself. 

32.  It  should  be  noted  that  though  Cyprus  appears  to 
have  exported  its  own  manufactures  to  the  yEgean  during 
this  period,  it  was  not  in  a  position  to  influence  or  direct 
the  Cycladic  culture.  But  still  less  is  there  any  trace  that 
the  younger  and  more  vivacious  school  reacted  at  all  upon 
the  elder  ;  this  was  reserved  for  the  full-grown  culture  of 
Mykense. 

2,7,.  It  is  at  this  period  that  the  Cretan  evidence,  though 
as  yet  miserably  incomplete,  becomes  of  crucial  importance. 
Crete  shares,  to  begin  with,  the  early  bronze  age  civilisa- 
tion of  Hissarlik  and  Cyprus,  resembling  the  latter  more 
closely  ;  but  it  is  not  till  the  Cycladic  stage  is  reached  that 
we  have  more  than  the  most  fragmentary  evidence.  In  the 
Cycladic  period  and  in  the  succeeding  age  Crete  was  almost 
literally  tKaro^woXiQ,  the  "  island  of  an  hundred  cities,"  and 
certainly  exercised  a  vigorous  and  continuous,  perhaps  even 
a  predominant  influence  upon  /Egean  civilisation.  At  this 
point  the  wealth  and  variety  of  Cretan  decorative  art  become 
conspicuous,  and  a  chronological  point  of  the  very  first  im- 
portance and  a  clue  to  the  origin  of  some  characteristic 
motives  are  given  by  the  recent  demonstration  of  a  frequent 
and  fertile  intercourse  with  Egypt  in  the  time  of  the  twelfth 
Dynasty.  On  the  one  hand,  a  very  peculiar  and  local  fabric 
of  pottery  from  Kamarais  in  Crete  has  been  found  in  twelfth 
Dynasty  layers  at  Kahun  ;  on  the  other,  the  Cretan  types 
of  bronze  implements  are  typically  Egyptian,  and  twelfth 
Dynasty  scarabs  were  not  only  frequently  imported,  but 
commonly  imitated.      In  fact  it   is  very  probably  from  this 


PREHISTORIC  MAN,  ETC.  351 

quarter  that  the  spiral  motives,  which  are  dominant  in  the 
Egyptian  Art  of  the  twelfth  Dynasty,  were  introduced  into 
the  decorative  repertory  of  /Egean  art. 

34.  The  seal-stones  engraved  with  Egyptian  and  deriva- 
tive spirals  are  closely  associated  in  Crete  with  others 
bearing  groups  of  symbols,  more  than  eighty  of  which  have 
been  recorded,  and  shown  to  be  hieroglyphic,  by  Mr.  A.  J. 
Evans.  They  exist  in  two  series,  of  which  the  earlier  is  fully 
pictorial  and  naturalistic,  the  later  conventionally  abbre- 
viated into  linear  forms.  Some  of  the  former  are  closely 
analogous  to  certain  Egyptian,  others  to  certain  "  Hittite  " 
hieroglyphs  from  Kappadokian  monuments  ;  many  of 
the  latter  are  identical  with  graffiti  on  twelfth-eighteenth 
Dynasty  pottery  from  Kahun,  Tell-el-Hesy  and  elsewhere, 
and  some  are  probably  prototypes  of  symbols  which  per- 
sisted in  the  Phoenician,  Greek  and  Lykian  alphabets,  and 
in  the  Cypriote  syllabary.  This  hieroglyphic  system  is  not 
confined  to  Crete,  though  it  is  far  best  represented  there 
as  yet ;  the  pictorial  seal-stones  are  distributed  over  the 
Cycladic  area  ;  and  two  inscriptions  in  the  linear  character 
have  been  found  on  vases  at  Mykenae.  Dr.  Kluge,  of 
Magdeburg,  believes  that  he  can  translate  these  hiero- 
glyphic inscriptions  into  a  dialect  of  Greek. 

35.  We  now  come  to  what  is,  even  literally,  the  Golden 
Age  of  the  early  Mediterranean  cycle.  "  Mykensean  "  Art 
is  still  best  and  most  completely  illustrated  by  the  long 
series  of  discoveries  in  the  plain  of  Argos,  which  at  once 
revealed  its  existence,  and  have  given  to  it  a  name.  The 
monuments  and  the  civilisation  of  Mykenae  and  Tiryns 
have  been  repeatedly,  though  never  yet  really  adequately, 
described,  and  have  given  rise  to  the  most  divergent 
theories  as  to  their  date,  their  origin,  and  their  relations 
with  what  precedes  and  follows  them.  The  following 
points  are  those  which  are  chiefly  made  clear  by  the  most 
recent  researches. 

36.  The  limits  within  which  Mykensean  sites  are  dis- 
tributed may  now  be  defined  with  some  approach  to 
accuracy,  and  no  less  the  wider  area  over  which  Mykenaean 
civilisation  had  a  living  influence.     With  the  exception  of 

25 


352  SCIENCE  PROGRESS. 

the  "Sixth  City"  of  Hissarlik  no  Mykenaean  settlement  is 
known  on  the  mainland  of  Asia  Minor.  Isolated  vases  are 
reported  from  Pitane  in  JEoYis,  from  Mylasa  in  Karia,  and 
from  Telmessos  in  Lykia,  and  the  early  necropolis  of 
Termera  (Assarlik)  near  Halikarnassos  (Budrum),  though 
of  distinctly  indigenous  character,  is  strongly  influenced,  at 
the  very  end  of  the  period,  by  late  Mykenaean  models  from 
the  neighbouring  islands.  Among  the  latter,  besides  the 
great  settlement  at  Ialysos  in  Rhodes,  every  island  appears 
to  be  represented  from  Rhodes  southwards  to  Crete,  and 
northwards  as  far  as  Patmos.  Both  in  Melos  and  in  Thera 
Mykenaean  settlements  are  found  distinctly  superimposed 
on  the  Cycladic  already  mentioned,  and  others  are  indicated 
by  isolated  finds  throughout  the  Archipelago.  On  the 
mainland  of  Greece,  Lakonia  is  represented  by  two  sites 
Kampos  and  Vaphio  (Amyhlae),  the  latter  with  a  princely 
"beehive  tomb"  like  those  of  Mykenae ;  Argolis  by 
Mykense,  the  Heraion  temple-site,  Tiryns,  Nauplia, 
Trcezen,  Epidauros,  and  the  islands  Kalauria  and  ^gina  ; 
Attica  by  Athens,  Eleusis,  Acharnae  (Menidi),  Aliki,  Kara, 
Spata,  and  Thorikos ;  the  rest  of  Central  Greece  by 
Megara,  Antikyra,  Thebes,  Tanagra,  Levadia,  Orchomenos 
and  several  smaller  sites  in  the  Kopais  marshes;  North 
Greece  by  Pagasae  (Dimini  near  Volo)  in  Thessaly. 

$*].  In  the  West  there  are  no  Mykensean  settlements 
known  further  than  Kephallenia  and  Ithaka;  but  Mykensean 
vases  occur  in  domed  rock  tombs  at  Syracuse,  and  there  is 
much  indirect  evidence  of  Mykenaean  influence  on  the  later 
Bronze  Age  style  in  Sicily  and  South  Italy.  Further  than 
this,  it  is  clear  that  on  the  Adriatic  coast  of  Italy  Mykenaean 
imports  and  models  determined  the  character  of  the  later 
Bronze  Age,  and  that  in  the  transition  from  Bronze  to 
Iron  at  Hallstatt  in  the  Tyrol,  a  definitely  Mykenaean  strain 
can  be  detected.  But  in  both  these  cases  the  contact  is 
with  later  and  already  quite  decadent  types,  such  as  are  re- 
presented in  the  Lower  Town  of  Mykenae  ;  in  particular 
fibulae  are  always  present,  and  of  these  the  secondary  and 
distinctly  Sub-Mykenaean  types  are  only  very  rarely  absent. 

38.    Eastwards,  Mykensean  imports  are  found  frequently 


PREHISTORIC  MAN,  ETC.  353 

in  Cyprus,  in  the  latest  class  of  Bronze  Age  tombs, 
and  give  a  very  distinct  character  to  the  necropoleis 
of  Episkopi  (Kurion),  Enkomi  (Salamis),  Pyla,  Niko- 
lidhes,  and  Laksha-tu-Riu.  Native  imitations  increase  in 
frequency,  and  eventually  supersede  the  importations  and 
fix  the  leading  features  of  the  art  of  the  early  Iron 
Age,  e.g.,  at  Kuklia  (Paphos),  Lapathos  and  Katydata- 
Linu.  In  Egypt  again,  Mykenaean  importations  are  found 
in  great  quantity,  associated  with  the  later  Cypriote  fabrics 
and  stimulating  copious  native  imitation  in  layers  of  the 
eighteenth  Dynasty  at  Illahun,  Gurob,  Tell-el-Amarna. 
These  last  finds  confirm  the  date  already  inferred  from 
the  occurrence  of  eighteenth  Dynasty  scarabs  and  porcelain 
ornaments  at  Ialysos  and  at  Mykenae,  and  fix  the  general 
chronology  of  the  Mykenaean  Age  beyond  all  question.  The 
contrary  opinion,  that  the  Mykenaean  civilisation  immediately 
precedes  the  Orientalising  culture  of  the  seventh-sixth 
centuries,  and  consequently  itself  descends  as  late  as  the 
eighth-seventh  centuries,  has  been  vigorously  urged  by  a 
few  English  students,  but  has  long  been  abandoned  by  all 
who  have  had  first-hand  experience  of  the  conditions  of 
discovery.  The  premature  contention  that  the  fortress  of 
Tiryns  was  Byzantine  deserves  mention,  but  is  obsolete. 

39.  It  is  in  Egypt  also,  moreover,  that  the  first  notice 
occurs  of  the  actual  peoples  who  transmitted  the  civilisation 
in  question,  and  this  in  a  peculiarly  suggestive  connection. 
In  the  fifth  year  of  Merenptah  (1225)  and  under  Rameses 
III.  (1 1 80- 1 150)  the  western  frontier  of  Egypt  was  seriously 
threatened  by  a  Mediterranean  coalition,  of  which  the 
Libyans  were  the  principal  members,  but  which  included 
under  the  general  description  of  "  the  peoples  of  the  isles 
of  the  sea  "  a  number  of  tribes  whose  names,  though  much 
distorted  in  the  Egyptian  hieroglyphic  records,  strongly 
resemble  those  of  Achaians,  Danaans,  Ionians,  Teucrians, 
Tuscans  or  Tyrrhenians,  and  perhaps  Sicilians  and 
Sardinians.  Neither  these  names,  of  course,  nor  yet  the 
apparent  resemblance  of  their  arms  and  furniture,  as  depicted 
in  Egyptian  paintings,  can  give  more  than  a  plausible  pre- 
sumption of  identity  either  with  historical  /Egean  races  or 


354  SCIENCE  PROGRESS. 

with  the  representatives  of  Mykenaean  civilisation.  But  the 
analogies  are  on  all  sides  so  close,  that  the  identification  is 
usually  accepted,  and  that  as  soon  as  even  the  outlines  of 
the  history  and  civilisation  of  Libya  during  the  Bronze  Age 
are  ascertained,  we  shall  be  in  a  position  to  formulate 
the  real  relations  which  then  existed  between  Libya 
and  the  /Egean,  and  probably  also  to  trace  more  clearly  to 
its  source  the  very  remarkable  realistic  instinct  which  dis- 
tinguishes the  art  of  the  y^Egean  from  all  contemporary 
styles. 

40.  The  sudden  collapse  of  the  Mykensean  civilisation, 
which  was  indicated  to  begin  with,  is  roughly  coincident  with 
the  first  appearance  of  Iron  in  common  use  in  the  Levant,  and 
the  attempt  has  been  made,  though  on  no  direct  evidence, 
to  connect  the  two  tendencies.  All  the  facts  go  to  indicate 
that,  so  far  as  the  Mediterranean  area  is  concerned  at  all 
events,  iron  makes  its  appearance  first  on  the  Syrian  coast, 
in  the  period  which  immediately  succeeds  the  downfall  of 
Egyptian  suzerainty  in  that  area  under  the  nineteenth  and 
twentieth  Dynasties:  e.g.,  at  Tell-el-Hesy  iron  occurs  down  to 
the  fourth  "City"  (=  eighteenth  Dynasty).  The  ambiguity 
of  the  Egyptian  allusions  under  the  eighteenth  and  previous 
Dynasties  makes  any  earlier  date  uncertain,  and  iron  has 
not  been  actually  found  in  Egypt  before  the  twenty-sixth 
Dynasty,  650  B.C.  In  Cyprus,  where  the  evidence  is  com- 
pletest,  and  where  abundant  native  ores  have  certainly  been 
worked  from  an  early  period,  iron  suddenly  becomes  very 
common  just  at  the  point  when  Mykensean  vases  are  ceasing 
to  be  imported,  but  when,  on  the  other  hand,  Mykenaean 
conventions  have  already  begun  to  influence  profoundly  the 
native  scheme  of  ornament.  At  Mykenae  itself  iron  occurs 
first  as  a  "  precious  metal  "  and  in  the  form  of  signet  rings,  at 
the  stage  where  decadence  begins  to  be  rapid,  but  it  is  not 
put  to  practical  uses  till  the  moment  where  the  series  breaks 
off,  and  the  same  is  the  case  in  other  Mykenaean  sites  in 
the  iEgean  ;  one  iron  sword  was  found  in  the  Vaphio  "  bee- 
hive ". 

41.  Up  the  Adriatic  again  it  is  with  the  early  fibulae  and 
quite  degenerate  Mykenaean  art,  that  iron  makes  its  appear- 


PREHISTORIC  MAN,  ETC.  355 

ance,  at  Novilara  ;  and  at  Hallstadt  ;  and  here  again,  both  in 
tradition  and  among  the  finds,  there  is  evidence  that  the 
metal  became  established  first  as  an  ornamental  rarity,  and 
only  subsequently  as  a  substitute  for  bronze. 

42.  But  though  in  its  principal  centres  Mykensean 
civilisation  has  all  the  appearance  of  having  been  suddenly 
and  violently  extinguished,  this  must  not  be  taken  to  be 
universally  the  case.  In  Argolis  (at  Tiryns,  and  the  Heraion), 
in  Attica,  and  in  Melos,  for  example,  there  is  every  reason  to 
believe  that  the  Mykenaean  civilisation  survives,  though  in 
very  degenerate  phases,  into  the  period  when  Iron  and  the 
characteristic  art  of  the  early  Iron  Age  are  already  well 
established  ;  and  at  Nauplia  and  the  Attic  Salamis,  and 
still  more  in  Crete,  in  Karia,  and  in  Cyprus,  the  stages  may 
be  clearly  traced  by  which,  so  far  as  in  it  lay,  the  Iron  Age 
took  up  its  inheritance  from  the  Age  of  Bronze.  The 
nature  and  the  result  of  this  transference  are  easily  sum- 
marised. 

43.  It  has  been  already  indicated,  firstly,  that  through- 
out the  Eastern  Mediterranean,  in  fact  throughout  the  whole 
range  of  the  Mediterranean  Early  Bronze  Culture,  the 
indigenous  system  of  decoration  is  instinctively  rectilinear 
and  geometrical  ;  secondly,  that  in  the  Cycladic  area  and 
in  the  Middle  Bronze  Age  a  quite  irreconcilable  and  purely 
naturalistic  and  quite  heterogeneous  impulse  appears  ;  and 
thirdly,  that  the  fully  formed  Mykenaean  style,  when  it 
appears,  is,  in  spite  of  its  far  superior  technical  skill  and 
elegance,  already  beginning  to  stagnate  in  many  depart- 
ments ;  the  gem-engraving  and  modelling  developing  last, 
and  retaining  their  vigour  and  elasticity  latest ;  whereas 
the  ceramic  decoration,  which  appears  in  its  noblest 
form  at  Thera  and  at  Kamarais,  is  the  first  to  exhibit  the 
conventional  and  mechanical  repetition  of  a  shrinking 
assortment  of  motives.  We  may  now  add,  fourthly, 
that  this  failure  of  originality  permitted  of  a  recrudescence 
of  the  rectilinear  instinct  which,  though  overwhelmed  for 
the  time  by  the  naturalistic  and  curvilinear  principles,  had 
co-existed  with  them  throughout ;  and  that  both  floral  and 
spiral  motives,  once  allowed  to  repeat  themselves  without 


356  SCIENCE  PROGRESS. 

reference  to  their  models,  are  transformed  automatically 
into  the  latticed  triangles  and  maeanders,  which  are  the 
commonplaces  of  rectilinear  design. 

44.  At  this  point  the  survey  must  close,  for  now,  on 
geometrically  engraved  tripods,  and  geometrically  painted 
vases,  appear  Hellenic  inscriptions  in  alphabetic  characters. 
Borrowed  Oriental,  and  especially  Assyrianising,  motives 
intrude  themselves  into  the  panels  of  the  rectilinear  orna- 
ment, and  attempts  are  made,  however  ineffectual,  to 
represent  first  animal  and  then  human  forms.  Now,  in  the 
development  upward  out  of  the  "  Dark  Age,"  Hellenic 
history  begins  to  reckon  onward  from  the  Trojan  Era  and 
from  Olympic  and  kindred  lists  ;  and  Hellenic  art  no  longer 
forward  from  the  eighteenth,  but  backward  from  the  twenty- 
sixth  Dynasty. 

LEVANTINE  ETHNOLOGY,  AND  SUMMARY  (to  follow). 

BIBLIOGRAPHY. 

N.B.  The  references  which  follow  are  grouped  under 
the  numbers  of  the  paragraphs  of  the  text.  They  only 
indicate  the  primary  researches  and  theories,  and  must  be 
compared  with  the  fairly  full  references  in  Perrot  and 
Chipiez,  Histoire  de  I  Art.  VI,  La  Grece  Prehistorique, 
1895,  and  with  the  current  notices  of  discoveries  scattered 
throughout  M.  Salomon  Reinach's  invaluable  "  Chroniques 
d'Orient "  published  in  the  Revtie  ArchcEologique,  of  which 
the  years  1883- 1890  have  been  republished  separately 
(Paris,  Firmin  Didot,  1891). 

6.  Dr.  Schliemann's  Researches. 

Schliemann.    Ilios.  (German  and  Englished.),  1881,  (French 
ed.,  including  "  Troja"),  1885,  (German  and  English),  1884. 
Atlas  Troj.  A Iterthumer  (photographs),  1874. 
Mycence  ,,  ,,  1878. 

Ithaka,  etc.,   ,,      ,,  1879. 

OrcJwmenos    ,,      ,,  1881. 

Tiryns     ,,  ,,  1886. 

SCHUCHHARDT.     ScJiliemanii  s  Excavations  (German,  Leipzig, 
1890);  E.  T.  Macmillan,  1891. 


PREHISTORIC  MAN,  ETC.  357 

11.  The    Stone    Age.      Sp.     LAMBROS.      'Ia-opiKa     MeXeryj/xara 

{Historical  Essays),  ch.  i. 
Dumont.     Materiaux  pour   servir    a   Fhistoire  primitive   de 

rhomme,  1872  (Finlay  Collection).  Revue  ArchcEologique,  xv., 

pp.  16-19,  356  ff.,  xvi.,  p.  359  (1867). 
PAPPADOPOULOS.      AiQwi)   kiroyy)  ev  rfj   Mifcpa   ' Aa'ia  (Stone 

Age    in    Asia    Minor),    Smyrna,    1875.       Cf.    Bulletin    des 

Correspondances  Helleniques,  ii.,  p.  8,  1876. 
FlNLAY.     UapaTtipriaei<i  {Observations),  Athens,  1869. 

13.  Psemmatismeno.     DtJMMLER.     Athenische  Mittheilungen,  xi., 

pp.  214-6,  1886. 
Bronze  Age  Tombs  with  Neolithic  Implements.    At  Kurion  in 
Cyprus.     Archives  des  Missions,  xvii.,  p.  6.     Cypr.  Museum 
Catalogue,  No.  470  (Oxford,  1 896).   At  Tiberiopolis  in  Phrygia. 
J.  A.  R.  Munro.    Journ.  Roy.  Geog.  Soc.  (forthcoming). 

14.  Ballas-Nagada.       Catalogue   of   Exhibits,     University    College, 

London,    July,    1895;     Academy,    20th    April,     16th   July, 
1895  (Report  forthcoming). 

15.  Jade.     SCHLIEMANN  (Maskelyne).     Ilios.  (English),  p.  240. 
FISCHER.     Neplirite   u.  Jadcite  .  .   .    uach   Hirer    Urgesch.    u. 

Ethnogr.  Bedeutung,  Stuttgart,  1875. 
Davies.     Geol.  Mag.,  second  decade,  v.,  4,  April,  1878. 

16.  Hissarlik,  v.  §  6,  SCHLIEMANN. 

NORMAND.     La  Troie  d'Homere  (popular,  well  illustrated). 

17.  Thymbra.     SCHLIEMANN.     Ilios.  s.  v. 

Boz-oyuk   (Phrygia).    Jahrbuch  d.    K.   Akademie,  Berlin,  xi., 

1896.      Anzeiger,  p.  34. 
Salonika.    Jahrbuch,  I.e. 
Thessaly.     Mitth.  Ath.,  p.  99  ff.,  1884. 

18.  Bceotia.    Jahrbuch,  1895.     Anzeiger,  p.  32. 

J.H.S.,  pp.  54-56,  figs.  10-13,  1884. 
Attica.     Mitth.  Ath.,  p.  138,  fig.  31,  1S93. 
Jahrbuch,  p.  16,  1893. 
22ff.  MUCH.  Die  Kupferzeit  in  Europa  (second  edition),  Jena,  1893. 
Naue.    Die  Bronzezeit  auf  Cypern.    Korresp.  Blatt,  p.  124,  1888. 
VlRCHOW.     Zeit.  d.  Deutsch.  Gesellsch.  d.  Anthrop.,  xii.,  73. 

27.  Copper  and  Early  Bronze  with  but  little  Tin.  J.  H.  GLADSTONE. 

Proc.  Brit.  Ass.  (Nottingham),  p.    715,  1893.      Trans.   Soc. 
Bibl.   Archeology,    xii.,    pp.    227-234.      Flinders    Petrie. 
Zeitschr.  f.  Ethu.,  p.  [477],  1891.     BLISS,  I.e. 
Tell-el-Hesy.     BLISS.     A  Mound  of  Many  Cities,  1894. 

28.  Cyprus.     Sandwith.     Archcsologia,  1877. 
DtJMMLER.     Mitt.  Ath.,  xi.,  1886. 
OHNEFALSCH-RlCHTER.     Kypros  the  Bible  and  Homer,  1892. 


358  SCIENCE  PROGRESS. 

Myres  and  OHNEFALSCH-RiCHTER.  Cyprus  Museum  Catalogue, 
Oxford.  1896  (in  the  press). 

30.  Thera.     FOUQUE.     Santorin.      Archives   des   Missions,  ser.   2, 

vol.  iv. 

31.  Cyclades.     Dummler.     Mitth.  Ath.,  xi.,  1886. 
Antiparos.     Bent.    /.  H.  S.,  x.,  1887. 

33.  Crete.     A.  J.  Evans.    Journ.  Hellenic  Studies,  xiv.,  pp.  276-372, 

1894  (republ.  "Cretan  Pictographs,"  etc.,  Quaritch,  1895). 

34.  y£gean  Hieroglyphic  System.     Evans,  I.e. 
KLUGE.     Magdeburger  Zeitung,  1896. 

35.  Mykenaean   Civilisation  in   general.      v.   Bibliogr.   in    PERROT, 

vi.,  q.v. 
TSOUNTAS.       Mvxrjvai    fcal     Muk.    ttoXlthtpos   (Mykenae    and 

Myk.  Civilisation),  Athens,  1893. 
TSOUNTAS.     sE^>rffi€pU  'ApxaioXoyL/cr)  {Journal  of  Gk.  Arch. 

Soc),  1 886- 1 894,  passim. 
PERROT    and    Chipiez.       Histoire    de    I'Art,    vi.    (la    Grece 

Prehistorique)   (E.  T.),  1895. 
FURTW/ENGLER  u.  LcESCHKE.     Myk.   TJiongefdsse,  1879. 
FURTW^ENGLER  U.    LcESCHKE.      Myk.    Vasen,  1886. 
POTTIER.      Vases  Antiques  du  Louvre,  I.,  p.  181  ff.,  1896. 
HELBIG.     La  Question  Myce'nienne.     Paris,  1896. 
^6.  Mykenaean  Sites,  Asia  Minor  : — 

Hissarlik,    "VI."       DCERPFELD.       Troja,    1893.       Mykenische 
Vasen,  p.  n.     Reinach.     Rev.  Arch.,  1893,  i.,  p.  357.    Rev. 

Arch.,  1895,  i.,  p.  1 13. 
Pitane  (zEolis).     PERROT,  vi.,  Fig.  489-91. 
Lemnos.     Rev.  Arch.,   xxvii.,    1895,   Nov. -Dec.  ;   cf.   Smyrna 

Museum. 
Telmessos.     Mitth.  Ath.,  xii.,  pp.  228-230. 
Thessaly.    WOLTERS.    Mitth.  Ath.,  xiii,  p.  262,  PI.  viii.-xi.,  1889. 
Orchomenos   and    neighbourhood.      SCHLIEMANN,   q.v.      De 

Ridder.    B.  C.  H.,  p.  137  ff.,  1895.    Esp.  Gha.    De  Ridder. 

B.  C.Lf.,p.  271  ff.,  1894.     Noack.     Mitth.  Ath,,  xix.,  1894. 
Daulis.     {Athens:  National  Museum),  unpublished. 
Antikyra  (Phokis).      Lolling.        Wolters'    Mitth.    Ath.,    xiii., 

p.  267,  1889  (identified  with  Medeon). 
Athens.     TSOUNTAS.     *E<f>.  'Apx-,  1891,  p.  27  ff. 

GR/EF.     Jahrbuch,  1892.     Anzeiger,  p.  16  ff. 
Wide.    'Adtjvcuop,  ii.,  1895,  168. 
Eleusis.     Philios.     'Ecp.  'Apx-,  1889,  p.  171. 
Koropi.      Bruckner.      Mitth.  Ath.,  xvi.,  p.   200  ff.,    18 

(identified  with  Pallene). 
Sal  am  is.     (Athens:  National  Museum.) 


PREHISTORIC  MAN,  ETC.  359 

/Egina.     Evans.    /.   H.   S.,  p.  195  ff.,  1892-93  (Gold-find). 

Reinach.      Rev.  Arch.,  November-December,  1895. 
Kalaureia.     Wide.     Mitth.  At//.,  xx.,  p.  297,  1895. 
Troezen.     Reinach.     Chroniques,  p.  628. 

Epidauros.     [Athens:  National  Museum.)    'Apx  AeXrlov,  1888. 
Kephallenia.     Wolters.     Mitth.  Ath.,  xix.,  pp.  486-490. 
Crete.     Milchhcefer.     Die  Anfange  d.  Kunst,  p.  122  ff. 
Evans.    /.   H.   S.,  xiii.,  pp.  276-372,   1894    (republ.   "Cretan 

Pictographs,"  Ouaritch,  1895). 
FURTW.ENGLER  u.  LCESCHKE.      Myk.    Vaseil,  pp.  22-4. 
Halbherr  and  ORSI.     Museo  Italiano,  II.,  p.  908,  pi.  xiii.-xiv. 
Haussoullier.    B.  C.  H.,  1880,  pp.  124-7. 
Joubin.     B.  C.  H.,  1892,  p.  295. 
ORSI.     Monumenti  AnticJii  d.  Accad.  d.  Lincei,   I.,  p.   201   ff., 

1890. 
Perrot,  vi.,  p.  451  ff.  (bibliography). 
Sicily.      ORSI.     Bulletino  di  Paletnologia  Italiana,  xviii.,  pp. 

193  ff.,  206  ff ,  xx.,  p.  257  ff.     Necropoli  Sieu/a,  p.  30  ff. 
Spain.     GASCON  de  GOLOS.     Saragoza,  i.,  pi.  iii.,  p.  40. 
39.  Chronology — For  eighteenth  Dynasty  dates  : — 

Flinders  Petrie.    /.  H.  S.,  xii.,  pp.  199-205,  1891. 
Perrot,  vi.,  p.  1000  ff. 
For  later  dates  (summary)  :  — 
REINACH.     Chroniques,  pp.  420,  575  ff     Rev.  Arch.,  p.  75,  1893. 

Classical  Review,  p.  462  ff,  1892.      Times,  6th  January,  1896. 

Academy,  nth  January,  cf.  1st  February,  1896. 
Torr.     Memphis  and  Mykence.     1896. 
For  "  Byzantine  "  Tiryns  (summary)  : — 

Reinach.     Chroniques,  p.  280  ff,  V Anthropologic,  p.  701,  1893. 

J.   L.   Myres. 


THE    GRAPTOLITES. 

THERE  is,  perhaps,  no  better  illustration  in  geology  of 
the  value  of  detailed  work  than  that  which  is  fur- 
nished by  the  group  of  organisms,  to  the  consideration  of 
which  this  article  is  devoted.  Formerly  viewed  with  sus- 
picion by  biologist  and  geologist  alike,  and  frequently 
altogether  ignored,  we  find  the  graptolites  now  treated 
with  respect  even  by  those  who  have  not  devoted  special 
attention  to  them.  Their  value  is  generally  recognised  as 
aids  in  the  determination  of  the  age  of  strata,  but  besides 
this,  a  detailed  study  of  the  group  will  undoubtedly  throw 
light  upon  the  physical  and  climatic  conditions  under  which 
the  strata  containing  graptolite  remains  were  deposited,  and 
also  upon  the  evolution  of  the  various  forms  of  graptolites. 
Every  one  will  admit  that  the  appreciation  in  which  grapto- 
lites are  now  held  is  largely  due  to  three  papers  by  Professor 
Lapworth,  one  of  which  treats  of  these  organisms  from  a 
biological  (i),  and  the  second  (2)  and  third  (3)  from  a 
stratigraphical  point  of  view  ;  and  the  publication  of  these 
papers  is  doubtless  largely  responsible  for  the  appearance 
of  a  large  number  of  memoirs  devoted  to  a  study  of  the 
group  under  consideration  which  have  been  written  of 
recent  years.  These  recent  memoirs  it  is  the  object  of 
this  paper  to  consider. 

The  memoirs,  early  and  more  recent,  treating  of  the 
graptolites  are  scattered  through  a  variety  of  publications, 
but  an  excellent  bibliography  compiled  by  Otto  Herrmann 
and  published  in  his  Inaugural  Dissertation  (4)  gives  a  list 
of  these  memoirs  up  to  and  including  the  year  1883.  Even 
with  this  guide  the  student  has  much  difficulty  in  obtaining 
access  to  some  of  the  publications,  and  a  general  monograph 
of  the  graptolites  has  yet  to  be  written.  In  the  list  of 
"  Monographs  which  are  promised  or  are  in  course  of 
publication "  appended  to  the  last  "  Monograph  of  the 
Palaeontographical  Society"  we  note  "The  Graptolites,"  by 
Professor  Lapworth,  and  all  geologists  must  hope  that  ere 


THE  GRAPTOLITES.  361 

long  the  professor  will  give  to  the  world  the  full  results  of 
his  prolonged  researches  into  the  history  of  the  group. 
This  monograph  must  necessarily  be  confined  to  an  account 
of  the  British  graptolites,  but  when  that  is  complete  surely 
Professor  Lapworth  will  treat  of  those  of  other  countries 
also. 

The  graptolites,  at  one  time  referred  by  some  writers  to 
the  Hydrozoa,  by  others  to  the  Polyzoa,  are  now  generally 
admitted  to  belong  to  the  former  class,  though  the  exact 
value  of  the  sub-division  is  not  definitely  settled,  for  whereas 
we  find  Professor  von  Zittel  in  his  Paleontology  treating  of 
them  as  a  sub-order,   Graptolithidse  (=  Rhabdophora,  All- 
man),   divided   into  the  groups   Graptolitoidea    Lapw.    and 
Retioloidea   Lapw.,   Nicholson  and   Lydekker  {Manual  of 
Paleontology)  place  them   in  a  sub-class   (Graptolitoidea). 
In  these  works  the  general  structure  of  the  graptolites  is 
described,  though,  as  will  be  seen  in  the  sequel,  one  structure 
supposed  to  be  absolutely  characteristic  of  all  graptolites, 
namely  the   virgula,  is  not  really  so.      Comparatively  little 
has  been  added  to  the  knowledge  of  the  histology  of  the 
graptolitoidea  furnished  by  H.  Richter  (5),  though  some  of 
his  results  have  been  confirmed  by  Professor  Sollas  (6)  ; 
and  additional   information  has  been  supplied  by  Professor 
S.  L.  Tornquist  (7)  and  Dr.  Perner  (8).      Some  of  the  most 
important  papers  published  of  recent  years  treat  especially 
of  the   mode  of  growth   of  the   proximal   portions   of  the 
graptolites.      The  first  of  these  by  Tornquist  (9)  is  occupied 
with  a  description  of  sections  through  several  deprionidian 
graptolites.      The  author  distinguishes  the  obverse  from  the 
reverse   aspect   of  the   polypary,   and   also   introduces   two 
terms  to  distinguish  its  right  and  left  portions — the  "  primor- 
dial "  portion,  containing  the  "primordial"  series  of  hydro- 
thecae,  is  marked  by  the  possession  of  the  earliest  hydro- 
theca,   whilst   the   other  portion   is   termed   the    "second" 
portion   and   possesses   the    second    series    of  hydrothecse. 
When  the  obverse  aspect  of  the  polypary  is  turned  towards 
the    observer    the    primordial    series    of  hydrothecae   is   in- 
variably on  the  left  hand.     The  sicula  sends  out  what  the 
author   terms   a    "  connecting   canal  '    which    opens   into   a 


362  SCIENCE  PROGRESS. 

"  biserial  chamber,"  thus  producing  a  connection  between 
the  various  parts  of  the  polypary.  These  features  are 
common  to  all  the  forms  described  by  the  author,  but  the 
forms  differ  in  other  respects.  In  Climacograptus  scalaris 
Linn,  and  Climacograptus  internexus  Tornq.  the  biserial 
chamber  communicates  with  two  uniserial  canals  separated 
from  one  another  by  a  median  septum.  In  Diptograptus 
palmeus  Barr.  the  septum  scarcely  extends  through  half  the 
thickness  of  the  polypary,  whilst  in  Cephalograptus  cometa 
Gein.  it  is  "  reduced  to  a  narrow7  fold  of  the  obverse  peri- 
derm," and  in  Diptograptus  bellutus  Tornq.  it  is  altogether 
absent. 

Two  papers  by  Wiman  (10)  treat  of  the  structure  of  the 
Diptograptidce  and  of  Monograptus.  Notices  of  these  papers 
by  E.  M.  R.  Wood  and  G.  L.  Elles  appear  in  the  Geological 
Magazine  for  1895,  p.  431.  The  accounts  of  the  structure 
of  the  sicula,  and  of  those  parts  of  the  polypary  immediately 
in  contact  with  it,  are  largely  confirmed  by  Holm  in  a  paper 
to  be  noticed  immediately,  but  the  statement  that  the  Dip- 
tograptida;  are  monoprionidian  because  the  sicula  gives  rise 
to  only  one  bud  (which  is  on  the  right  hand  side)  involves 
a  special  use  of  the  term  monoprionidian  which  will  hardly 
meet  with  general  acceptance. 

A  most  important  paper  by  Gerhard  Holm  must  now  be 
noticed  (11).  Holm  has  had  the  advantage  of  studying 
some  beautiful  material  derived  from  the  J^aginatus-Yimestone 
(of  Areing  age)  from  various  localities  in  the  northern  part 
of  the  Island  of  Oland  ;  the  graptolites  of  this  limestone  he 
has  succeeded  in  freeing  from  the  matrix,  thus  rendering 
them  serviceable  for  detailed  study.  (The  method  of  re- 
moving the  matrix  is  described  by  Holm  in  an  article  in 
Bihang  K.  Vetensk.  Akad.  HandL,  Bd.  xvi.,  1890.)  In  the 
present  paper  he  gives  reasons  for  supposing  "that  the 
earlier  development  of  the  proximal  part — the  first  three 
thecae — in  all  the  bilateral  or  diprionidian  forms  of  graptolites 
is  in  the  main  the  same,  and  has  taken  place  through  the 
formation  of  only  one  bud  on  one  side  of  the  sicula — -or  first 
theca,  as  I  believe  it  is — which  side  is  always  the  same  in 
relation  to  the  later  development  of  the  polypary.      From 


THE  GRAPTOLITES.  363 

this  bud  thereafter  is  developed  partly  the  second  theca, 
partly  the  canal — '  connecting  canal  ' — which  connects  both 
halves  of  the  polypary,  and  which  in  the  first  place  gives 
origin  to  the  third  theca  (=  first  theca  on  opposite  side  of 
sicula),  and  partly  also  the  common  canal  which  connects 
the  second  theca  with  the  succeeding  ones."  He  describes 
the  "  sicula "  which  consists  of  two  distinct  portions,  the 
"initial  part"  which  he  believes  to  correspond  with  the 
original  "  chitinous  covering  of  the  free  zooid  germ  or  em- 
bryo," and  the  apertural  part  which  has  the  same  function 
as  a  theca  and  may  therefore  be  justly  considered  as  the 
first  theca.  Accordingly  Holm's  second  theca  corresponds 
to  Tornquist's  primordial  one,  and  his  third  to  Tornquist's 
second. 

The  sicula  in  the  bilateral  graptolites  does  not  occupy  a 
central  position,  being  partly  embraced  on  one  side  by  the 
connecting  canal,  whilst  on  the  other  side  it  is  more  or  less 
superficial.  The  sicula  side  is  termed  the  "anterior,"  and 
the  other  the  "posterior".  These  are  used  in  the  same 
sense  as  that  in  which  Tornquist  employs  the  terms  "ob- 
verse aspect"  and  "reverse  aspect".  The  author  gives  a 
full  account  of  the  connection  between  the  sicula,  the  first 
theca,  the  first  bud,  from  which  "  arises  almost  simul- 
taneously with  the  left  theca  the  common  canal  for  the 
left  half  of  the  polypary,  and  the  connecting  canal  which 
crosses  the  dorsal  side  of  the  sicula  and  gives  origin  to  the 
third  (or,  better,  the  right)  theca  lying  on  the  right  side  of 
the  polypary,  and  also  the  common  canal  for  the  right  side 
of  the  polypary,"  and  describes  the  growth  of  these  in 
Didymograptus  minutus  Tornq.,  D.  gracilis  Tornq.  mut.,  D. 
gibberulus  Nich.,  Tetrgraptus  Bigsbyi  Hall,  and  Phyllo- 
graptus  angustifo/ius  Hall. 

He  maintains  that  a  virgula  cannot  occur  in  any 
graptolites  of  the  families  Dickograptida,  Dictyogr apt  idee, 
and  Nemagraptidce,  or  in  the  genus  Dicellograptus  of  the 
family  Dic7'anogiraptid&.  The  true  virgula  commences 
near  the  apex  of  the  sicula  as  a  prolongation  of  the  same, 
and  corresponds  with  the  thread-like  prolongation  of  the 
sicula    which    has    long    been     known    in    Didymograptus 


364  SCIENCE  PROGRESS. 

gibberulus,  and  certainly  occurs  in  many  other  forms  of 
Dichograptidce.  Another  filiform  appendage  which  might 
be  spoken  of  as  the  false  virgula  "  originates  as  a  result  of 
growth  within  the  apertural  end  of  the  sicula  at  some 
distance  from  the  initial  portion.  This  later  structure 
stands  evidently  in  no  relation  whatever  to  the  real 
virgula,  but  may  be  regarded  as  an  apertural  spine."  The 
significance  of  these  filiform  processes  has  not  yet  been 
fully  explained,  but  the  possession  of  a  true  virgula  must  in 
future  be  omitted  from  diagnoses  of  the  characters  of  the  sub- 
class or  sub-order  of  the  graptolites.  Holm's  researches 
fully  confirm  Tullberg's  inference  that  Phyllograptus  belongs 
to  the  family  Dichograptidce,  and  the  family  Phyllograptidcz 
must  now  be  abandoned.  Another  interesting  point  bear- 
ing upon  classification  is  the  position  from  which  the  bud 
grows  out  of  the  sicula.  "  In  Phyllograptiis  it  is  situated 
quite  close  to  the  apex  of  the  sicula,  in  Tetragraptus 
Bigs  by  i  Hall  probably  slightly  lower  down,  in  Didymograptus 
miniUus  Tornq.  somewhat  below  the  middle  of  the 
sicula,  in  Didymograptus  gracilis  Tornq.  Mut.  still  nearer 
the  aperture  ;  but  in  Didymograptus  gibberulus  Nich.  the 
position  is  almost  the  same  as  in  Pliyllograptus."  The 
reference  of  the  genus  Azygograptus  to  the  Nemagraptidce 
on  account  of  the  stipe  being  developed  from  the  central 
part  of  the  sicula  on  one  side  is  therefore  unnecessary,  and 
the  general  characters  of  Azygograptus  leave  no  doubt 
that  it  belongs  to  the  Dichograptidce ;  indeed  Holm  in  the 
paper  under  consideration  describes  a  form  which  is  possibly 
intermediate  between  Didymograptus  and  Azygograptus. 

The  association  of  a  number  of  graptolites  of  the  same 
species  in  a  fairly  symmetrical  manner  has  long  been 
known.  James  Hall  in  plate  xiv.  of  his  classic  work  on 
graptolites  (12)  figures  a  diprionidian  graptolite  under  the 
name  of  Retiograptus  teutaculatus,  and  in  figure  9  is  "an 
illustration  of  a  compound  form  of  the  genus,"  possessing 
nearly  twenty  diprionidian  stipes  diverging  from  a  common 
centre.  James  Dairon  (13)  also  figures  specimens  of 
Monograptus  occurring  in  partly  symmetrical  tufts,  and 
remarks  :  "  I  am  now  thoroughly  convinced  that  many,  if 


THE  GRAPTOLITES.  365 

not  all,  of  the  specimens    of  Monograptus  may  have  been 
fixed  to   the  sea-bottom,  or  to  objects  lying  or  growing  on 
it,  and  not  have  been  free-floating  organisms,  as  has  hither- 
to been  supposed,  until  at   last  they  were  separated  from 
their   points   of    attachment    by   breakage    or    some    other 
natural   cause ".       Recently  a    remarkable  description    has 
appeared  (14)  giving  an  account  of  specimens  of  Dipto- 
graptus   pristis     Hall    and    D.    pristiniformis    Hall    from 
the  Utica  Slates.      In  these  specimens  the  stipes  occur  in 
"compound  colonial  stocks  which  appear  in  the  fossil  state 
in  stellate  groups  ".      From  observations  on  the  specimens, 
the  author  infers  "that  the  colonial   stock  was  carried  by  a 
large  air-bladder,  to  the  underside  of  which  was  attached 
the   funicle.     The   latter  was  enclosed   in  the  central  disc, 
and    this    was    surrounded    by    a    verticil   of  vesicles,    the 
gonangia,  which   produced   the  siculae.      Below  the  verticil 
of  gonangia  and   suspended   from  the  funicle  was  the  tuft 
of  stipes,"   the  latter  being  so   arranged   that  the  "  sicula- 
bearing  end  of  the   single  stipes  appears  in   the  compound 
colonial  stock  as  the  distal   one  ".       The  paper   is  only  an 
abstract  of   one  which   is   promised  shortly,  and  geologists 
will  await  with   interest  a  full  account  of  these  remarkable 
specimens.     The  structure  described  as  a  funicle  can  hardly 
be  looked  upon  as  the  analogue  of  the   "  organ"  described 
by    Hall    under  that  name    (which    by   the  way  has  been 
proved  by  Brogger  and   Holm  to  be   celluliferous  in   many 
species,  so  that  Holm  is   doubtless  correct  when  he  says 
that    a  funicle  has   not  been  found   in  any  graptolite).      It 
is   remarkable    that     the  author    should    explain    what    he 
means  by  the  assertion   that  the    chitinous  capsule  which 
encloses    the     "  funicle ':    on   the    specimens    described    is 
identical     with     the     "central    disc ':     of    the     compound 
fronds    of   numerous    Monogr apt  idee,   for    no   geologist,    as 
far  as   I  am  aware,  has  described  Monograptidcc  with  com- 
pound fronds,  unless  Dairon's  specimens  be  taken  as  such. 
The  early  writers  on  graptolites  looked  upon  the  num- 
ber  of  stipes    possessed    by   graptolites  as  a  character   of 
prime  importance  in   defining  genera,  such  forms  as  Dicho- 
graptus,     Tetr agraphia,    Didymograptus  and   Monograptus 


366  SCIENCE  PROGRESS. 

being  largely  characterised  by  the  possession  of  eight,  four, 
two  stipes  and  one  stipe  respectively.  In  a  recent  paper 
by  Professor  Nicholson  and  the  present  writer  (15)  we 
have  endeavoured  to  show  that  this  is  not  the  case,  but 
that  the  character  of  the  hydrothecae  and  to  a  less  degree 
the  amount  of  angle  of  divergence  of  the  stipes  are  of  im- 
portance. We  endeavour  to  prove  that  certain  grapto- 
lites  underwent  development  along  parallel  lines,  passing 
through  many-branched,  eight-branched,  four-branched, 
two-branched  and  one-branched  forms,  thus  illustrating  the 
principle  of  heterogenetic  homoeomorphy  advocated  by 
Mojsisovics,  S.  S.  Buckman  and  others.  If  this  be  allowed, 
many  of  the  present  genera  will  have  to  be  abolished  and 
new  ones  formed  ;  but  the  writers  earnestly  advocate  the 
retention  of  the  present  genera  under  existing  circum- 
stances, and  hope  that  the  formation  of  fresh  genera  will 
be  deferred  until  our  views  are  more  fully  developed  or 
perchance  disproved,  though  we  do  not  think  that  the  latter 
event  is  likely. 

It  will  be  noticed  that  the  above  researches  into  the 
morphology  of  the  graptolites  deal  mainly  with  the 
celluliferous  portions  of  the  polyparies,  whilst  the  study  of 
the  various  bodies  referred  to  as  concerned  in  reproduction 
has  not  been  largely  pursued  of  recent  years. 

Passing  now  to  the  memoirs  treating  of  the  graptolites 
as  indices  of  age  of  the  rocks  which  contain  them,  it  may 
be  remarked  at  the  outset  that  recent  work  has  fully  estab- 
lished the  correctness  of  the  views  advanced  by  Lapworth 
in  his  papers  on  the  Moffat  series  and  on  the  geological 
distribution  of  the  Rhabdophora.  Perner  alone  has  stood 
out  for  the  anomalous  occurrences  described  by  the  eminent 
Barrande  in  the  Bohemian  basin,  but  he  does  not  yet 
appear  to  have  studied  completely  the  zonal  distribution  of 
these  organisms  in  that  region,  though  he  has  added  largely 
to  the  number  of  species  occurring  in  the  Lower  Palaezoic 
rocks  of  Bohemia.  The  new  species  described  here  and 
elsewhere  of  recent  years  it  is  not  contemplated  to  notice  in 
this  article,  though  they  will  doubtless  give  us  much 
information  in  addition    to   that   we   have  already  obtained 


THE  GRAPTOLITES.  367 

concerning  the  morphology  and  phylogeny  of  the  graptoli- 
toidea.  It  would  serve  no  useful  purpose  to  give  details  of 
the  numerous  papers  which  confirm  the  value  of  the  grap- 
tolites  for  purposes  of  correlation  of  the  strata.  In  Britain, 
Lapworth  himself  has  described  a  number  of  graptolitic 
bands  interstratified  with  deposits  containing  the  remains  of 
other  organisms  in  Ayrshire  (16).  Much  remains  to  be 
done  in  this  respect,  for  in  order  to  utilise  to  the  utmost  the 
value  of  these  organisms  as  stratigraphical  indices,  it  will  be 
necessary  to  have  a  complete  correlation  of  graptolitiferous 
strata  of  all  ages,  with  those  which  contain  these  organisms 
rarely  or  not  at  all.  For  this  purpose  all  graptolites  should 
be  carefully  collected  and  preserved  from  out  of  those 
deposits  in  which  they  are  not  frequent,  and  are  associated 
with  other  organisms.  They  should  be  looked  for  especi- 
ally in  calcareous  deposits,  for  as  we  have  already  seen,  such 
specimens  are  particularly  valuable  as  furnishing  information 
concerning  the  morphology  of  these  fossils.  The  southern 
uplands  of  Scotland  have  recently  been  re-examined  by  the 
geological  surveyors,  and  it  is  scarcely  necessary  to  state 
that  they  have  fully  confirmed  Professor  Lapworth's  classifi- 
cation of  the  Lower  Palaeozoic  Rocks  of  this  region.  In 
England  Professor  Nicholson  and  the  present  writer  have 
defined  graptolitic  zones  in  the  Skiddaw  Slates,  Llandovery, 
Tarannon,  Wenlock  and  Lower  Ludlow  Beds  (17).  Messrs. 
Lake  and  Groom  have  detected  the  Monograptus  gregarius 
zone  of  the  Birkhill  shales  and  zones  of  Monograptus  per- 
sonalis, M.  Flemingii,  M.  colonius  and  M.  leint  wardinensis 
near  Corwen  and  Llangollen  (18),  whilst  in  a  paper  which 
has  hitherto  only  appeared  in  abstract,  Miss  Wood  and 
Miss  Elles  have  detected  several  zones  of  the  Birkhill-Gala 
beds  near  Conway.  On  the  Welsh  borderland  W.  W. 
Watts  has  found  one  graptolitic  zone  of  Wenlock  and  two 
of  Lower  Ludlow  age  on  the  Long  Mountain  (19).  In 
addition  to  this,  various  other  graptolitic  zones  have  been 
detected  in  different  parts  of  Great  Britain,  and  the  zones  of 
the  Moffat  area  have  been  traced  into  Ireland.  On  the 
European     continent,      Linnarsson,     Brogger,     Tornquist, 

Tullberg  and  others    have    detected    numerous    graptolite 

26 


368  SCIENCE  PROGRESS. 

zones  in  Scandinavia,  a  full  account  of  which  appears  in 
Tullberg's  paper  on  the  graptolites  of  Scania  (20),  one  of 
the  most  valuable  of  recent  contributions  to  the  literature  of 
the  graptolites.  Tornquist,  Perner,  Barrois  and  others 
have  also  identified  various  graptolitic  zones  in  Thuringia, 
Bohemia  and  France.  In  North  America  the  principal 
contribution  is  by  our  own  countryman,  Lapworth,  who  has 
identified  a  number  of  graptolite  zones  in  Canada,  which 
are  identical  with  those  detected  in  Europe  (21).  In 
Australia  T.  S.  Hall  is  studying  the  well-known  Areing 
graptolite  fauna,  and  finds  that  the  graptolites  here  also  are 
limited  to  special  zones  (22).  A  number  of  other  papers 
might  be  quoted  to  show  the  general  recognition  of  the 
utility  of  graptolites  for  purposes  of  correlation  of  strata, 
but  enough  has  been  said  to  indicate  the  manner  in  which 
the  work  is  progressing,  and  the  vast  amount  which  yet 
remains  to  be  done  in  this  connection.  I  cannot  leave  this 
part  of  the  subject  without  uttering  a  warning  note.  More 
harm  is  done  by  a  wrong  determination  than  good  by  a 
correct  one.  The  graptolites  are  by  no  means  easy  of 
identification  by  those  who  have  not  made  them  a  special 
study,  and  it  is  particularly  desirable  that  no  determination 
should  be  recorded  by  tyros,  unless  it  is  absolutely  certain, 
for  when  once  a  wrong  name  has  crept  into  a  list  it  is 
exceedingly  difficult  to  remove  it.  I  could  give  several 
instances  of  very  serious  mistakes  of  this  kind  which  have 
been  made,  each  of  which  will  have  to  be  corrected  else- 
where, but  it  would  be  invidious  to  give  names  in  a 
general  article  of  this  character. 

We  may  now  pass  on  to  consider  the  physical  conditions 
under  which  the  graptolite-bearing  strata  were  deposited. 
There  is  very  little  doubt  that  they  were  formed  in  water  of 
very  different  degrees  of  depth,  for  graptolites  are  found  in 
arenaceous,  argillaceous  and  calcareous  strata.  Thev  have 
mainly  been  collected  from  deposits  which  there  is  every 
reason  to  suppose  were  formed  in  deep  seas,  because  a  much 
greater  number  of  individuals  occur  in  a  given  space  under 
such  conditions  than  when  the  deposits  were  formed  rapidly. 
The  writer  has  elsewhere  given  cases  of  graptolitic  deposits 


THE  GRAPTOLITES.  369 

a  few  feet  in  thickness,  being  represented  by  thousands  of 
feet  in  adjoining  regions,  and  one  naturally  discovers 
forms  more  easily  in  a  few  feet  of  strata  than  in  several 
thousand  feet  where  the  process  of  search  rather  closely 
approximates  to  that  for  the  proverbial  needle  in  the  hay- 
stack. The  evidence  which  is  being  gathered  shows  more 
strongly  than  ever  that  the  thin  graptolite-bearing  shales, 
which  for  the  above  reasons  have  come  to  be  looked  upon 
as  the  deposits  for  graptolites /di?'-  excellence,  were  deposited 
slowly  in  waters  some  distance  from  continents,  and  pro- 
bably of  considerable  depth.  The  evidence  for  depth 
depends  mainly  on  the  nature  of  the  associated  organisms, 
which  are  frequently  dwarfed,  and  either  blind  or  with 
enormously  developed  eyes,  whilst  that  for  deposition  at 
a  distance  from  land  is  confirmed  by  the  ever-increasing 
number  of  cases  of  association  of  graptolitic  deposits  with 
others  which  are  composed  almost  exclusively  of  tests  of 
radiolaria.  The  most  striking"  case  of  this  has  recently 
been  detected  by  the  geological  surveyors  amongst  the 
rocks  of  the  Southern  uplands  of  Scotland  (23).  Messrs. 
Peach  and  Home  have  there  discovered  beds  with  Tetra- 
graptus  of  Middle  Areing  Age,  separated  from  beds  with 
characteristic  Glenkiln  (Upper  Llandeilo)  graptolites  by  a 
thin  deposit  of  radiolarian  chert.  "  We  thus  perceive  that 
the  great  mass  of  strata  which  elsewhere  forms  the  Upper 
Areing,  and  the  Lower  and  Middle  Llandeilo  formations 
are  here  reduced  to  not  more  than  sixty  or  seventy  feet. 
Judged  by  the  palaeontological  evidence  these  thin  cherts 
appear  to  be  a  chronological  equivalent  of  thousands  of  feet 
of  ordinary  sediment  in  North  Wales.  They,  no  doubt, 
were  deposited  with  extreme  slowness  in  a  sea  of  some 
depth,  and  over  a  part  of  the  sea-floor  which  lay  practically 
outside  the  area  of  the  transport  and  deposit  of  the  terres- 
trial sediment  of  the  time." 

The  graptolites  are  generally  viewed  as  type-fossils  of 
the  Lower  Palaeozoic  rocks,  and  this  view  is  practically 
correct.  The  earliest  graptolite  which  has  hitherto  been 
described,  Dichograptus  ?  tenellns  Linnrs.,  occurs  in  the 
Lingula  Flags  of  Sweden,  below  the  shales  with  Dictyo- 


370  SCIENCE  PROGRESS. 

graptus flabelliformis  Eichw.  which  are  so  widely  distributed. 
This  Dictyograptus,  by  the  way.  which  has  a  very  limited 
vertical  distribution,  is  probably  in   no  way  related  to  the 
long-ranged  Dictyonema.      Graptolites  are  extremely   rare 
in  the  Upper  Ludlow  rocks,  and  have  been  detected  in  the 
Lower   Devonian  rocks  of  Bohemia,  though   it  is  doubtful 
whether  their  asserted  occurrences  in  rocks  of  Devonian 
age  in  Scotland  and  the   Harz   Mountains  are  correct.      It 
may  be  taken  as  fairly  certain  that  they  finally  died  out  in 
Devonian  times.     Between  the  earliest  and  latest  graptolitic 
deposits  we  have  already  a  large  number  of  graptolitic  zones, 
which  it  will  be  of  use  to  print  in  one  connected  list  as  this 
has  not  been  heretofore  done.      So  far  as  they  have  been 
made  out  they  are,  in  ascending  order,  as  follows  :  Lingula 
Flags  ;  (i.)  Zone  of  Dichograptus?  tenellus,  Zone  of  Dictyo- 
graptus flabelliformis.      Tremadoc  Slates;  Zones   of  Bryo- 
graptus.      Areing  Beds ;    Zones  of  (i.)  Dichograptus,   (ii.) 
Tetragraptus,    (iii.)    Didymograpttts    indentus    var   nanus. 
Llandeilo  Beds;    (i.)  Zone  of  Didymograpttts  Murchisoni, 
(ii.)   Zone  of  Ccenograpttis  gracilis.     Bala  Beds;  Zones  of 
(i.)   Climacograptus  Wilsoni,   (ii.)  Dicranograptus  Clingani, 
(iii.)  Pleurograptus  linearis,  (iv.)  Dicellograptus  complana- 
tus,  (v.)  Dicellograptus  anceps.     Llandovery  Beds ;  Zones  of 
(i.)  Diplograptus  acuminatus,  (ii.)  Diplograptus  vesiculosus, 
(iii.)   Monograptus  argenteus,  (iv.)  Monograptus  convolutus, 
(v.)    Cephalograptus  cometa,    (vi.)  Monograptus  spinigerus, 
(vii.)  Rastrites  maximus.      Tarannon  Beds ;    Zones  of  (i.) 
Monographts  turriculatus,  (ii.)  Monograptus  exiguus,    (iii.) 
Cyrtograptus   Graycz.       Wenlock  Beds;    Zones   of  various 
species  of  Cyrtograptus  not  yet  fully  worked  out.      Lower 
Ludlow  Beds;  Zones  of  (i.)  Monograptus  bohemicus,   (ii.) 
Monograptus  Alilssoni,  (iii.)  Monograptus  leintzvardinensis. 
Upper  Ludlozv  and  Lower  Devonian  ;  Zones  of  undescribed 
graptolites. 

It  is  quite  certain  that  this  number  will  be  very  largely 
increased  as  a  result  of  further  work,  but  it  is  sufficient  to 
show  the  importance  of  the  Lower  Palaeozoic  rocks  when  it 
is  remembered  that  many  of  these  Zones  contain  a  fauna 
largely   distinct    from    the    faunas    of   the    adjoining    ones. 


THE  GRAPTOLITES.  371 

When  the  Zones  are  worked  out  more  fully  than  is  the 
case  at  present,  we  shall  have  a  far  better  gauge  of  "  Geo- 
logical Time  "  than  that  founded  upon  the  crude  estimates 
made  by  measuring  thicknesses  of  strata. 

Lastly,  the  study  of  graptolites  may  possibly  throw 
some  light  upon  climatic  change.  I  have  already  en- 
larged upon  this  elsewhere  (24),  and  pointed  out  that  the 
separation  of  graptolitic  deposits  from  non-graptolitic  ones 
amongst  the  Stockdale  shales  of  the  Lake  District,  the 
deposits  themselves  being  lithologically  similar,  is  most 
readily  explicable  by  climatic  change.  The  argument 
would  be  stronger  had  microscopic  examination  and 
chemical  analyses  of  the  strata  been  made,  and  I  should 
be  glad  to  supply  any  one  who  cares  to  look  into  this 
question,  which  is  one  of  some  interest,  with  material  for 
such  examinations. 

In  conclusion,  the  above  notes  will  be  sufficient  to 
show  the  importance  which  the  graptolitoidea  have 
assumed  not  only  to  the  geologist  but  also  to  the  biologist. 
That  they  differ  in  any  remarkable  respect,  as  regards 
their  teachings,  from  any  other  group  of  fossils  is  doubtful. 
Their  special  utility  lies  in  the  fact  that  owing  to  their 
characters  they  are  preserved  in  sufficient  numbers  to 
allow  collectors  to  obtain  a  large  suite  of  specimens  of 
almost  every  species  with  little  difficulty  ;  the  result  is  that 
further  advance  has  been  made  in  their  study  than  in  that 
of  many  other  groups  which  like  them  are  only  preserved 
in  the  fossil  state.  One  word  to  the  biologists.  We  are 
often  told  that  fossils  are  of  little  use  on  account  of  the 
absence  of  soft  parts,  though  biologists  have  not  been 
much  hampered  by  this  when  dealing  with  the  Vertebrata. 
But  to  compensate  for  the  want  of  soft  parts,  we  are  furnished 
with  a  countless  supply  of  specimens  whose  order  of  appear- 
ance and  disappearance  we  are  able  to  a  large  extent  to  ascer- 
tain, and  this  is  what  the  biologist  can  never  obtain  by  con- 
fining his  attention  to  recent  organisms.  From  them  he  has 
been  able  to  ascertain  that  evolution  occurs;  how  it  occurs 
is  left  for  the  palaeontologist  to  describe.  That  the  study 
of  these  organisms  as  pursued  up  to  the  present  has  not 


372  SCIENCE  PROGRESS. 

been  in  vain,  is  conclusively  proved  by  the  best  of  all  tests, 
namely,  that  we  are  able  to  predict  the  discovery  of  forms 
which  are  afterwards  detected  by  the  worker   in   the  field, 
to  whom  we  commend  this  group  as  one  specially  worthy  of 
his  attention. 

BIBLIOGRAPHY. 

(i)  LAPWORTH,  Charles.  Notes  on  the  British  Graptolites  and 
their  Allies.  I.  On  an  improved  Classification  of  the 
Rhabdophora.     Geol.    Mag.,    vol.    x.,    pp.     500    and     555, 

1873. 

(2)  LAPWORTH,  CHARLES.      The  Moffat  Series.     Quart.  Journ. 

Geol.  Soc,  vol.  xxxiv.,  p.  240,  1878. 

(3)  LAPWORTH,   CHARLES.     On   the   Geological   Distribution    of 

Rhabdophora.      Ann.  and  Mag.  Nat.  Hist.,  ser.   5,  vol.   iii., 
1879. 

(4)  Herrmann,  Otto.     Die  Graptolithen  familie  Dichograptidae, 

Lapvv.     Kristiania,  1885. 

(5)  RlCHTER,  H.     Thiiringische  Graptolithen.     Zcit.  d.  Deutsch. 

Geol.  Gesell.,  vol.  v.,  p.  439,  1853. 

(6)  SOLLAS,  W.  J.     On  the  Minute  Structure  of  the  Skeleton  of 

Monograptus  priodon.  Rep.  Brit.  Assoc.,  1893,  P-  7%l> 
1894. 

(7)  TORNQUIST,  S.  L.     Studier  ofver  Retiolites.     Aftr.  nr  Geol. 

Foren.  i.  Stockholm  Forhdndl,  Bd.  v.,  7,  p.  292,  1880. 

(8)  Perner,  J.     Etudes  sur  les  Graptolites  de  Bohbne.     Prague, 

1894. 

(9)  TORNQUIST,  S.   L.     Observations  on   the   Structure  of  some 

Diprionidae.  Sdrtryck  of  Konl.,  Fysiogr.,  Svesk.,  Handl. 
Ny  Folgd.,  1892-3,  Bd.  iv.     Lund,  1893. 

(10)  Wiman,  Carl.      Ueber  Diplograptidae  Lapw.,    and    Ueber 

Monograptus  Geinitz.  Bull.  Geol.  Inst.,  Univ.  Upsala,  vol. 
i.,  1893. 

(11)  Holm,  G.      Om   Didymograptus,   Tetragraptus  och   Phyllo- 

graptus.  Aftr.  ur  Geol.  Foren.  i.  Stockholm  Forhdndl., 
1895,  translated  by  Miss  Wood  and  Miss  Elles  in  Geol. 
Mag.,  vol.  ii.,  pp.  433  and  481,  4th  Dec. 

(12)  Hall,  James.     Graptolites  of  the  Quebec  Group,  1865. 

(13)  Dairon,  James.     Notes  on  Graptolites.      Trans.  Geol.  Soc, 

Glasgow,  p.  176,  1882. 

(14)  Ruedemann,   R.      Synopsis  of  the   Mode   of  Growth    and 

Development  of  the  Graptolitic  genus  Diplograptus.  Amer. 
Journ.  Sci.,  vol.  xlix.,  3rd  ser.,  p.  453,  1895. 


THE  GRAPTOLITES.  373 

(15)  NICHOLSON,  H.  A.,  and  Marr,  J.  E.    Notes  on  the  Phylogeny 

of  the  Graptolites.     Geo/.  Mag.,  4th  Decade,  vol.  ii.,  p.  529. 

(16)  Lapworth,  C.     The  Girvan  Succession.     Quart.  Joum.  Geo/. 

Soc,  vol.  xxxviii.,  p.  537. 

(17)  Marr  and  NICHOLSON.    On   the  Stockdale  Shales.     Quart. 

Joum.  Geo/.  Soc.,  vol.  xliv.,  p.  654.  Also  Marr.  On  the 
Wenlock  and  Ludlow  Strata  of  the  Lake  District,  Geo/.  Mag., 
3rd  Dec,  vol.  ix.,  p.  534,  and  Notes  on  the  Skiddaw  Slates, 
ibid.,  4th  Dec,  vol.  i.,  p.  122. 

(18)  Lake   and    GROOM.      On    the   Llandovery   and    Associated 

Rocks  of  the  Neighbourhood  of  Corwen.  Quart.  Joum. 
Geo/.  Soc.,  vol.  xlix.,  p.  426.  And  P.  Lake,  On  the  Denbigh- 
shire Series  of  South  Denbighshire,  ibid.,  vol.  ii.,  p.  9. 

(19)  Watts,  W.  W.     The  Geology  of  the  Long  Mountain  on  the 

Welsh  Borders.     Rep.  Brit.  Assoc.,  1890,  p.  817,  1891. 

(20)  TULLBERG,  S.  A.    Skanes  Graptoliter.    Sver.  Geo/.  Undersokn., 
_     ser.  C,  Nos.  50  and  55. 

(21)  Lapworth,  C.     Preliminary  Report  on  some  Graptolites,  etc. 

Trans.  Roy.  Soc.  Canada,  p.  167,  1886. 

(22)  HALL,  T.  S.     The  Geology  of  Castlemaine,  etc.     Trans.  Roy. 

Soc.  Victoria,  p.  57,  1895? 

(23)  Geikie,  Sir  A.     Annual  Report  of  the  Geo/ogicai  Survey,  etc., 

for  1895,  p.  27,  1896. 

(24)  MARR,  J.  E.     On  Homotaxis.     Proc.   Cambridge  Phi/.   Soc, 

vol.  vi.,  pt.  ii.,  p.  74. 

J.   E.    Marr. 


INSULAR   FLORAS. 

PART  VI.  (b). 

IN  my  article  (59)  on  the  flora  of  the  African  Islands  of 
the  Indian  Ocean,  I  dealt  with  the  subject  in  consider- 
able detail,  but  beyond  the  vascular  cryptogams  I  had  very 
few  data  concerning  the  Isle  of  Bourbon.  Since  then 
Dr.  Cordemoy  has  published  a  Flora  of  the  island  (60), 
which  is  a  consolidation  of  all  the  materials  he  has  been 
able  to  collect  during  the  leisure  of  upwards  of  thirty  years' 
residence  in  the  island,  though  unfortunately  without  a  full 
collation  with  the  rich  earlier  collections  in  the  Paris  Her- 
barium of  Commerson,  Du  Petit-Thouars,  and  other  botanists. 
Moreover,  he  has  not  worked  out  the  geography  of  the 
plants  to  the  extent  he  might  have  done,  so  that  it  takes 
some  time  to  find  and  extract  the  particulars  of  special 
interest  to  the  geographer.  Indigenous  and  naturalised 
plants  are  included  in  the  same  enumeration  without  any 
typographical  distinctions  ;  and  the  summary  is  limited  to 
a  table  showing  the  number  of  species  of  each  natural 
order,  including  naturalised  species.  A  rough  calculation 
of  the  number  of  indigenous  species  of  vascular  plants, 
described  or  enumerated,  gives  a  total  of  about  11 00, 
whereof  200  are  ferns,  and  172  are  orchids.'  This  is  nearly 
250  higher  than  Baker's  estimate  (61)  of  the  vascular  plants 
of  Mauritius;  but,  although  the  islands  are  nearly  of  the  same 
size,  the  mountains  of  Bourbon  rise  to  altitudes  of  between 
9000  and  10,000  feet,  or  about  6000  feet  above  those  of 
Mauritius  ;  thus  giving  an  additional  climatic  zone  to  the 
former  island.  And  an  analysis  of  the  components  of  the 
flora  shows  that  Bourbon  possesses  a  much  larger  temperate 
element.  But  it  should  be  known  that  Cordemoy  takes  a 
narrower  view  of  species  than  Baker,  especially  in  ferns  ; 
and  some  allowance  would  have  to  be  made  for  this  in  com- 
paring the  totals.  Apart  from  this  divergence,  the  flora  of 
the  two  islands  is  essentially  the  same,  several  genera  and 
many  species  being  common   to  both   and   found   nowhere 


INSULAR  FLORAS.  375 

else.  The  predominating  natural  orders  of  vascular  plants 
occupy  nearly  the  same  positions  numerically  in  both  islands  ; 
ferns  being  first  and  orchids  second,  and  Leguminosae  and 
Compositae  relatively  low  down  ;  very  different  proportions 
from  those  obtaining  in  the  Madagascar  Mora,  in  which 
these  four  orders  occupy  reversed  positions.  Thus  :  Legu- 
minosae, Filices,  and  Compositae,  followed  by  the  Orchideae, 
which  are  represented  by  just  half  as  many  species  as  the 
Leguminosae. 

The  absence  of  a  number  of  natural  orders  from  Dr. 
Cordemoy's  Flora  that  are  represented  in  Mauritius  may 
be  accounted  for  partly  by  the  fact  that  he  did  not  work  out 
the  old  collections  made  before  the  destruction  of  the  virgin 
forests  which  formerly  clothed  the  island.  It  is  probable 
that  many  species  have  disappeared  from  both  islands  from 
the  same  cause.  The  following  orders  known  to  be,  or  as 
having  been,  represented  in  Mauritius  are  not  included  by 
Cordemoy  :  Xyridaceae,  Scitamineae,  Podostemaceae,  Myo- 
porineae,  Bignoniaceae,  Lentibulariaceae,  Gentianaceae, 
Rhizophoreae,  Connaraceae,  Simarubaceae,  Ochnaceae,  Bur- 
seraceae  and  Nymphaeaceae.  The  absence  of  several  of  the 
foregoing  orders  might  be  accounted  for  without  calling  in  the 
theory  of  destruction,  but  it  would  lead  too  far  to  attempt  the 
discussion  of  the  matter  here.  Myoporum  mauritianum  is 
an  instance  of  a  plant,  and  an  order  that  is  no  longer  repre- 
sented, if  it  ever  were  ;  for  there  may  have  been  an  error 
in  locality.  The  only  specimen  at  Kew  is  labelled  as  coming 
from  one  small  patch  at  the  east  end  of  the  island  of 
Rodriguez,  which  is  some  300  miles  distant  from  Mauritius. 
Moreover  the  Seychelles  and  Rodriguez  between  them 
possess  several  natural  orders  which  do  not  reach  Bourbon 
or  Mauritius,  though  they  are  represented  in  Madagascar. 
They  are  Nepenthaceae,  Passifloraceae,  Turneraceae,  Diptero- 
carpeae  (?),  Ternstrcemiaceae  and  Dilleniaceae  ;  whereof  the 
first  and  the  fourth  are  essentially  Asiatic,  the  second 
and  third  American,  and  the  two  last  equally  Asiatic 
and  American.  The  parasitical  Rafflesiaceae  are  perhaps 
the  only  natural  order  in  Bourbon  that  is  not  repre- 
sented in  Mauritius.     Cordemoy  records  Hydnora  afncana 


376  SCIENCE  PROGRESS. 

as  common  at  St.  Paul  in  Bourbon.  It  inhabits  Eastern 
tropical  and  South  Africa,  though  it  is  not  known 
from  Madagascar  or  any  other  of  the  African  islands.  Six 
or  seven  species  of  Hydnora  have  been  described  ;  all  in- 
habiting Africa  from  Abyssinia  and  Angola  southward  to 
Cape  Colony.  I  have  previously  noted  (62)  the  discovery  of 
a  member  of  this  order  (Cytinus  Baroni)  in  Madagascar. 
Since  writing  that  I  have  seen  a  third  Mexican  species. 

The  intimate  relationships  of  the  floras  of  Bourbon  and 
Mauritius  may  be  gathered  from  the  presence  in  the  two 
islands,  and  restriction  to  these  islands,  of  the  following 
monotypic,  mostly  very  distinct,  genera:  Cossignya  and  Dora- 
toxylon  (Sapindacese),  Grangeria  (Rosaceae),  Roussea  (Saxi- 
fragaceae),  Psiloxylon  (Lythracese  ?),  Fernelia  (Rubiacese), 
Heterochcenia  (Catnpanulacese),  Bryodes  (Scrophularineae), 
Monimia  (Monimiaceae)  Dictyosperma  (Palmae).  To  these 
may  be  added  several  other  genera  of  the  same  geographical 
area,  represented  by  more  than  one  species  ;  in  five  instances 
out  of  six  by  three  species  :  Fostidia  (Myrtaceae),  Pyrostria 
and  A/y 07itma (Rub'iacedz),  Faujasia  (Composite),  Hyophorbe 
and  Acanthophcehix  (Palmae).  Twenty-five  other  character- 
istic genera  are  restricted  to  the  African  region,  using  that 
designation  in  the  sense  of  including  therein  the  islands 
under  consideration,  Madagascar,  and  continental  Africa. 
Trochetia  (Sterculiaceae)  is  remarkable  among  them  as 
extending  to  St.  Helena,  where  it  is  represented  by  two 
distinct  species — or  rather  was,  for  one  is  quite  extinct  in 
a  wild  state.     Psiadia  (Composite)  has  the  same  range. 

Allusion  has  been  made  (63)  to  the  phenomenal  con- 
centration of  endemic  palms  in  the  Seychelles,  and  it  would 
be  interesting  to  give  the  distribution  and  affinities  of  the 
palms  of  the  whole  of  the  East  African  Islands  ;  but  I  must- 
confine  myself  to  the  Bourbon  species.  The  native  species 
are  five  in  number,  namely :  Latania  Commersonii,  Hyophorbe 
indica,  Dictyosperma  album,  Acanthophcenix  rubra  and  A. 
crinita.  All  these  palms  also  inhabit  Mauritius,  and 
they  are,  so  far  as  our  present  knowledge  goes,  confined  to 
the  island.  All  the  genera  are  peculiar  to  this  insular  region 
if  we   take  in    Madagascar,  and   Dictyosperma  and    Acan- 


INSULAR  FLORAS.  377 

thophcenix  to  Mauritius  and  Bourbon.  Latania  belongs  to 
the  Borasseae  and  all  the  rest  to  the  Arecinese.  As  stated 
before,  there  is  no  parallel  to  this  in  insular  floras  of  other 
parts  of  the  world.  Polynesia,  both  the  eastern  and  western, 
is  relatively  poor  in  palms,  and  the  West  Indian  Islands 
possess  few  endemic  species  ;  but,  as  explained  a  few  pages 
back,  Lord  Howe  Island  possesses  four  endemic  species 
of  palms  belonging  to  Australian  and  endemic  genera. 

Coming  down  to  species  we  find  that  Cordemoy  de- 
scribes about  200  new  ones,  which,  with  those  previously 
known  as  endemic,  would  make  probably  not  less  than  25 
per  cent,  of  the  vascular  plants  endemic.  It  is  probable 
that  this  number — the  number  of  new  species — maybe  subject 
to  some  reduction,  especially  in  such  groups  as  the  ferns 
and  grasses  in  which  so  many  species  have  a  wide  range  ; 
yet  25  per  cent,  of  endemic  species  is  possibly  below 
rather  than  above  the  mark.  Nineteen  grasses  are  de- 
scribed as  new.  Considering,  however,  the  general  distribu- 
tion of  grasses,  and  that  only  four  species  are  regarded  as 
endemic  in  Mauritius,  there  are  good  grounds  for  suspect- 
ing that  many  of  the  Bourbon  species  are  not  really  new. 

Orchids,  epiphytal  and  terrestrial  combined,  contribute 
no  fewer  than  seventy  new  species  ;  and  the  total  number 
of  orchids  thus  exceeds  the  total  indigenous  species  of  any 
other  two  natural  orders.  In  Mauritius,  orchids  are  more 
numerous  than  any  other  order  of  flowering  plants,  but 
they  only  occupy  the  first  place  by  a  majority  of  about  ten. 
As  I  have  shown  elsewhere  (64)  orchids  are  exceedingly 
rare  or  entirely  wanting  in  oceanic  islands,  and  such  pro- 
portions as  Cordemoy's  enumeration  gives  would  hardly 
be  found  in  the  richest  orchid  districts  of  Asia  or  America. 
Continental  tropical  Africa,  so  far  as  known,  is  relatively 
poor,  whilst  in  Madagascar,  according  to  Baron's  tabulation 
(65),  orchids  stand  third,  being  exceeded  by  Compositae  and 
Euphorbiaceae.  It  is  true  that  I  have  estimated  (66)  that 
orchids  are  numerically  more  strongly  represented  in  British 
India  than  any  other  order  of  flowering  plants,  and  my 
estimate  has  proved  correct  in  the  subsequent  elaboration 
of  this  order  (67)  by  Sir  Joseph   Hooker.      It  may  be  in- 


378  SCIENCE  PROGRESS. 

teresting  to  add  that  orchids  stand  third  in  the  flora  of  the 
whole  world,  and  they  also  take  the  same  position  in  the 
flora  of  Mexico  and  Central  America. 

Returning  to  the  Bourbon  orchids  ;  the  regional  char- 
acteristic AngrcBCum  is  credited  with  eighteen  new  species, 
and  a  total  of  thirty-two  species.  There  are  also  new 
species  of  the  epiphytal  genera  Bulbophyllum,  Aeranthus, 
and  Saccolabinm ;  but  the  bulk  of  the  new  ones  are  terres- 
trial plants,  many  of  them  very  rare  and  inconspicuous,  and 
most  of  them  of  short  duration  above  ground. 

On  this  point  Cordemoy  says :  "  J 'en  ai  moi  meme 
plusieurs  nouvelles,  en  herbier,  que  leur  mauvais  etat  de 
conservation  ne  permet  pas  de  decrire.  Certainement  il 
en  existe  d'autres  non  encore  decouvertes,  surtout  parmi 
les  Ophrydees,  dont  plusieurs  parcourent,  en  quelques 
semaines,  la  periode  active  de  leur  vegetation,  puis  se 
replient  immediatement,  pour  passer  le  reste  de  l'annee  sous 
terre  a  l'etat  de  tubercule.  Plusieurs  localites  n'ont  pas  ete 
suffisament  explorees.'r 

Three  new  genera  of  this  group  are  described,  namely, 
Acrostylia,  Camilleugenia  and  Hcmiperis ;  the  first  two 
being  monotypic  and  the  third  having  twenty-one  species 
ascribed  to  it.  All  three  would  be  included  under  Habenaria 
by  some  authors  ;  but  in  this  extended  sense  Habenaria  is 
a  vast  and  heterogeneous  agglomeration  of  species. 

Among  other  genera,  of  which  several  new  species  are 
described,  I  may  mention  Dombeya,  Evodia,  Eugenia, 
Embelia,  Sideroxylon,  Geniostoma,  Psiadia  and  Faujasia. 

In  addition  to  the  new  genera  of  orchids,  four  others 
are  proposed,  namely,  Guya  (Bixaceae),  Herya  (Celas- 
tracese),  Allocalyx  (Scrophulariacese),  and  Mahya  (Labiatae). 
According  to  the  author's  own  admission,  three  out  of 
the  four  are  somewhat  doubtful,  and  the  affinity  of  the 
fourth  is  not  given  more  definitely  than  by  placing  it  in  the 
tribe  Menthese.  But  Alahya  stellata  is  an  interesting  plant, 
whatever  its  affinity,  because  it  is  believed  to  be  the  only 
really  indigenous  member  of  the  Labiatae.  It  is  a  dwarf 
shrub,  very  rare,  and  found  only  near  the  summit  of  the 
Grand  Benard,  at  an  elevation  of  about  8650  feet. 


INSULAR  FLORAS.  379 

Strange  to  say  the  upper  zone  of  vegetation  is  less 
alpine  in  character  than  that  of  the  mountains  of  Mada- 
gascar and  Tropical  Africa.  Cruciferae,  Caryophylleae, 
Umbelliferae,  Primulaceae  and  Gentianacese,  as  well  as  her- 
baceous Rosacese  and  Saxifragaceae,  are  either  exceedingly 
rare  or  entirely  absent.  In  Madagascar,  where  the  highest 
point  is  barely  8500  feet,  the  following  familiar  genera 
occur :  Ajuga,  Alckemilla,  Cattcalis,  Crassula,  D?-osera, 
Epilobium,  Genista,  Geranium,  Linum,  Pimpinella,Sanicula> 
Stachys,  and  Viola,  besides  many  others  which  are  unknown 
among  the  native  plants  of  Bourbon. 

Gymnosperms  are  also  unrepresented,  both  in  the  indi- 
genous vegetation,  and  among  the  numerous  naturalised 
plants.  It  is  the  same  in  Mauritius  ;  but  in  Madagascar 
one  species  each  of  Cycas  and  Podocarpus  has  been  dis- 
covered ;  the  latter  being  prominent  in  certain  districts. 

Finally,  I  may  add  that  the  following  orders  are  strongly 
represented  in  the  Bourbon  flora  :  Malvaceae  (Dombeya,  2 1 
species,  and  Ruisia,  Astiria,  and  Trocketia,  regional 
genera) ;  Rutaceae  (Evodia)  ;  Urticaceae  (Ficns,  and  Obetia 
and  Maillardia,  regional  genera)  ;  Euphorbiaceae  and  Con- 
volvulaceae. 

Since  the  untimely  death  of  Dr.  H.  Baillon  another 
part  (68)  of  the  admirable  illustrations  of  the  flora  of 
Madagascar  has  appeared.  It  consists  largely  of  plates 
for  intercalation,  and  the  highest  number  is  340.  Unfor- 
tunately no  descriptive  or  explanatory  letter-press  has  been 
published  in  connection  with  these  plates  and  none  is  likely 
to  be  forthcoming.  Surgeon-Major  H.  H.  Johnston  has 
published  (69)  an  enumeration  of  plants  collected  by  him- 
self and  regarded  by  him  as  indigenous  in  Mauritius, 
though  they  are  not  included  in  Baker's  Flora.  The 
total  is  fifty  species,  half  of  which  are  cellular  crypto- 
gams. There  is  nothing  specially  remarkable  amongst 
them.  The  same  gentleman  has  published  an  account  (70) 
of  the  vegetation  of  the  small  islands  in  the  Mahebourg 
Bay,  Mauritius,  namely  :  He  de  la  Passe,  He  Vakois,  He 
aux  Fouquets,  He  aux  Fous,  He  Marianne  and  Rocher  des 
Oiseaux.     These  islands  are   of  coralline  limestone  forma- 


380  SCIENCE  PROGRESS. 

tion,  and  their  flora  is  equally  as  poor,  and  composed  mainly 
of  the  same  species  as  the  flora  of  the  small  coral  islands  of 
the  Pacific  Ocean,  a  specimen  of  which  is  given  some  pages 
back. 

BIBLIOGRAPHY. 

(i)  Science  Progress,  i.,  pp.  26-35. 

(2)  J.  T.  Arundel.      The  Phoenix  Group  and  other  Islands  of  the 

Pacific,  8vo,    pp.   8.      Reprint     from     The    New    Zealand 
Herald,  5th  and  12th  July,  1890. 

(3)  Report  of  the  Eclipse   Expedition  to  Caroline   Island,  May, 

1883.     Memoirs  of  the  National    [American]    Academy  of 
Sciences,  ii.,  pp.  1-146,  with  a  number  of  views,  etc.     Botany, 
pp.  88-90,  by  W.  Trelease,  1884. 

(4)  C.    M.    WOODFORD.      The    Gilbert    Islands.       Geographical 

Journal,  vi.,  pp.  325-350,  with  a  map.     Botany,  p.  346,  1895. 

(5)  W.  Botting  HEMSLEY.      The  Flora  of  the  Tonga  or  Friendly 

Islands,  with  Descriptions  of  and   Notes  on   some  New  or 
Remarkable    Plants,    partly    from    the    Solomon     Islands. 
Journal  of  the  Linnean  Society,   xxx.,  pp.  158-217,  tt.  9-1 1, 
1894. 

(6)  J.  J.  Lister.     The  Geology  of  the  Tonga  Islands.     Quarterly 

Journal  of  the  Geological  Society,  xlvii.,  pp.  590-617,  with 
maps  and  views,  1891. 

(7)  W.    Botting    Hemsley.      Flora  of  the    Solomon    Islands. 

Kew  Bulletin  of  Miscellaneous  Information,  1 894,  pp.  211- 
215;  1895,  pp.  132-139;  1896,  p.  17;  and  Journ.  Linn.  Soc, 
xxx.,  pp.  163-165,  and  211-217,  plates  9-1 1,  1894. 

(8)  HOOKER'S  Icones  Plautarum,  t.  17 14. 

(9)  K.  SCHUMANN.     Die  Flora  von  Kaiser  Wilhelms  Land,  p.  69, 

1889. 

(10)  J.  G.  BOERLAGE.     Handleiding  tot  de  Kennis  der  Flora  van 

Nederlandsch  Indie,  i.,  p.  445  et  p.  673,  1890. 

(11)  C.  Hedley.      The  Range  of  Placostylus.     Proceedings  of  the 

Linnean  Society  of  New  South  Wales,  ser.  2,  vii.,  pp.  335- 
339,  1892. 

(12)  Science  Progress,  i.,  p.  40,  1894. 

(13)  H.  N.  Ridley.     A  Day  at  Christmas  Island.    Journal  of  the 

Straits  Branch  of  the  Royal  Asiatic  Society,  No.  23,  pp.  123- 
140,  1891. 

(14)  H.  Trimen.     Handbook  of  the  Flora  of  Ceylon,  part  ii.,  Con- 

naraceae  to  Rubiacese,  1894;  part  iii.,  Valerianaceae  to 
Balanophoraceae,  1895. 


INSULAR  FLORAS.  381 

(15)  H.  Trimen.     A  Preliminary  List  of  Maldive  Plants.    Journal 

of  Botany,  pp.  3-6,  1896. 

(16)  Capt.  VV.  F.  W.  Owen.     Geography  of  the  Maldiva  Islands. 

Journ.  Roy.  Geogr.  Society,  ii.,  pp.  81-92,  1832. 

(17)  Science  Progress,  i.,  pp.  387-396. 

(18)  T.  Kirk.      Trans,  and  Proc.  N.  Zeal.  Inst,  xxvii.,  pp.   327- 

359,  i895- 

(19)  W.  Colenso,    H.  C.  Field,   and    D.   Petrie.     Trans,  and 

Proc.  N.  Zeal.  Inst.,  xxvii.,  1895. 

(20)  A.     Hamilton.       Notes    on    a   Visit   to    Macquarie    Island. 

Transactions  and  Proceedings  of  the  New  Zealand  Institute, 
xxvii.,  pp.  559-579,  1895. 

(21)  Science  Progress,  L,  p.  395. 

(22)  Flora  of  Macquarie  Island.     Keiv  Bulletin,  p.  401,  1894. 

(23)  T.  KlRK.     On  the  Flora  of  Macquarie  Island.     Report  of  the 

Third  Meeting  of  the  Australasian  Association  for  the 
Advancement  of  Science,  pp.  226-227,  1891. 

(24)  T.  KlRK.     Description  of  New  Grasses  from  Macquarie  Island. 

Trans.  N.  Zeal.  Inst.,  xxvii.,  p.  353. 
(25)1  A.    Vollmer.     Lord    Howe    Insel,    Pitcairn    und    Norfolk 
Insel.     Petermann's  Mittheilungen,  xli.,  pp.  72--JJ,  1895. 

(26)  C.  MOORE.     Sketch  of  the    Vegetation   of  Lord  Howe  Island. 

A  Report  to  the  Under  Secretary  for  Lands,  New  South 
Wales,  1869. 

(27)  G.  BENTHAM.     Flora  Australiensis. 

F.  v.  MUELLER.     Fragmenta  Phytograpihce  Australia. 

(28)  J.  B.  WILSON.     Report  to  the  Colonial  Secretary  on  the  Present 

State  and  Future  Prospects  of  Lord  Howe  Island,  1  vol.  4to. 
With  Photographs.  List  of  timbers,  p.  22.  Vegetation  by 
J.  Duff,  pp.  28-36,  1882. 

(29)  ETHERIDGE.     Lord  Howe  Island ;  its  Zoology,  etc.,  1889. 

(30)  F.  VON  Mueller.     Index  omnium  Insulae  Howeanae  Plantar- 

urn,  quas  hactenus  obtenui,  exclusis  speciebus  certe  introduc- 
tis.    Fragmenta  Phytographia  Australia,  ix.,  pp.  76-78,  1875. 

1  Since  my  remarks  on  the  flora  of  Lord  Howe  Island  were  put  into 
type,  I  have  seen  the  "  Macleay  Memorial  Volume,"  published  by  the 
Linnean  Society  of  New  South  Wales,  in  1893.  It  contains  a  paper  by 
Prof.  R.  Tate  "  On  the  Geographic  Relations  of  the  Floras  of  Norfolk  and 
Lord  Howe  Islands,"  in  which  the  author  arrives  at  much  the  same  conclu- 
sions as  myself.  I  had  also  overlooked  a  short  article  by  Mr.  C.  Moore 
{Transactions  of  the  Royal  Society  of  New  South  Wales,  v.  (1872),  pp.  29- 
34),  on  the  same  subject,  but  dealing  only  with  the  distribution  of  the 
genera.  I  may  add  that  my  detailed  account  of  the  vegetation  and  flora 
of  the  island  has  appeared  in  the  Annals  of  Botany  for  June,  1896. 


382  SCIENCE  PROGRESS. 

(31)  O.  Beccari.     Malesia,  i\,  p.  66,  1877. 

(32)  Science  Progress,  i.,  p.  400. 

(33)  B.  L.  Robinson  and  J.  M.  Greenman.     On  the  Flora  of  the 

Galapagos    Islands.      American    Journal  of  Science,  1.,   pp. 
135-149,  1895. 

(34)  W.  BOTTING  Hemsley.     The  Flora  of  the  Galapagos  Islands. 

Nature,  lii.,  p.  623,  1895. 

(35)  G.  Baur.    The  Galapagos  Islands.    Proceedings  of  the  Ameri- 

can Antiquarian  Society,  1891 ,  and  Reprint,  1892  ;  and  a  fuller 
account  in  Bio/ogisches  Centralblatt,  xii.,  pp.  221-250. 

(36)  G.  Baur.     The  Differentiation  of  Species  on  the  Galapagos 

Islands  and  the  Origin  of  the  Group.  Biological  Lectures 
delivered  at  the  Marine  Biological  Laboratory  of  Wood's  Ho  11, 
1894,  pp.  67 -7S. 
($7)  A.  Agassiz.  General  Sketch  of  the  Expedition  of  the 
Albatross.  Bulletin  of  the  Museum  of  Comparative  Zoology 
at  Harvard  College,  xxiii.,  pp.  1-89,  plates  1-22,  including 
two  maps,  1892. 

(38)  Botany  of  the  "Challenger"  Expedition,  \.,  1,  Introduction,  p.  5. 

(39)  J.  D.  HOOKER.     On  the  Vegetation  of  the  Galapagos.     Trans- 

actions of  the  Linnean  Society,  xx.,  pp.  235-262,  1847. 

(40)  C.  Darwin.     A  Naturalists  Voyage,  p.  393,  edition  of  1884. 

(41)  A  Naturalist's  Voyage,  p.  396. 

(42)  W.  BOTTING  Hemsley.    Cactacese  in  the  Galapagos  Islands. 

Nature,  liii.,  p.  31,  1895. 

(43)  Magazine  of  Zool.  and  Bot.,  i.,  p.  467,  pi.  14,  f.  2,  1837. 

(44)  A  Naturalists  Voyage,  pp.  374  and  382,  edition  of  1884. 

(45)  Om  Galapagos  Oarnes  Vegetation.     Freg.  "  Eugenics"  Resa. 

Bot.,  p.  95. 

(46)  Biologischcs  Centralblatt,  xi.,  1892. 

(47)  J.   D.  Hooker.     Botany  of   Ellesmere    Land   and   Grinnell 

1 

Land.     Nares's  Narrative  of  a  Voyage  to  the  Polar  Sea,  ii., 
pp.  301-310,  1878. 

(48)  D.  Oliver.     List  of  Flowering  Plants  in  Ellesmere  Land  and 

Grinnell  Land,  8o°-83°  N.  lat.    Nares's  Narrative  of  a  Voyage 
to  the  Polar  Sea  during  1875-6,  ii.,  pp.  310-312,  1878. 

(49)  Science  Progress,  ii.,  p.  379,  1895. 

(50)  A.  Trevor-Battye.     Icebound  on  Kolguev.      Notes  on  the 

Flora,  pp.  396-417,  1895. 

(51)  H.    W.    Feilden.     Mild    Arctic    Climates.     The   Glacialists 

Magazine,  [.,  pp.  91-95,  1893. 

(52)  H.  W.   Feilden   and   H.   D.  Geldart.     Notes  on  a  small 

Collection  of  Spitzbergen  Plants.      Trans.  Norf  and  Norw. 
Nat.  Soc,  vi.,  pp.  47-53,  1894. 


INSULAR  FLORAS.  383 

(53)  F.    J.    Ruprecht.        Flores     Samoyedorum    Cisuralensium. 

Beitrdge  zur  Pflanzenkunde  des  Russischen  Reiches,  zweite 
Lieferung,  pp.  1-67,  tt.  1-6,  1845. 

(54)  H.  MOHN.      Einsamkeit   Insel.      Petermann's  Mittheilnngen, 

pp.  57-59,  1879. 

(55)  F.  KURTZ.     Verzeichniss  der  auf  Island  und  den  Faer  Oern 

von  Dr.  Konrad  Keilhack  gesammelten  Pflanzen.  Abhand- 
lungen  des  Botaniscken  Vereins  der  Piovinz  Brandenburg, 
xxxvi.,  pp.  150-158,  1895. 

(56)  J.  D.  Hooker.     On  the  Canarian  Flora  as  compared  with  the 

Maroccan.  Hooker  and  Ball's  Journal  of  a  Tour  in 
Marocco,  pp.  404-421,  1878. 

(57)  H.    Christ.       La    Flore     Ancienne     Africaine.       Archives 

des  Sciences  Physiques  et  Naturelles,  xxviii.,  pp.  369-374, 
1892. 

(58)  I.    Urban.       Additamenta     ad    cognitionem     Florae     Indiae 

Occidentalis.  Particula  2.  Engler's  Botanische  Jahrbiicher, 
xix.,  pp.  562-681,  1894-5. 

(59)  Science  Progress,  hi.,  pp.  447-75. 

(60)  E.  Jacob  de  CORDEMOY.     Flore  de  file  de  la  Reunion,  8vo, 

pp.  xxvii.  and  574,  1895. 

(61)  J.  G.  Baker.     Flora  of  Mauritius  and  the  Seychelles,  p.  15.* 

(62)  Science  Progress,  Hi.,  p.  457. 
(6^)  Science  Progress,  hi.,  p.  459. 

(64)  Botany  of  the  Voyage  of  the  "  Challenger,"  i.,  part  i.,  Introduc- 

tion, p.  27,  1885. 

(65)  Journal  of  the  Linnean  Society,  xxv.,  p.  252,  1889. 

(66)  Biologia  Centrali- Americana.     Botany,  i.,  p.  xv.,  1888. 

(67)  Flora  of  British  India,  v.,  pp.  667-910;  vi.,  pp.  1-198,  1888-90. 

(68)  H.  Baillon.     Histoire  Naturelle  des  Plantes  de  Madagascar. 

Atlas,  36e  Fascicule,  1895. 

(69)  H.    H.    JOHNSTON.     Additions   to   the   Flora   of    Mauritius. 

Transactions  of  the  Botanical  Society  of  Edinburgh,  1895. 
Reprinted  with  Additions,  pp.  28,   1896. 

(70)  H.   H.    JOHNSTON.     Report   on  the    Flora   of  the  Outlying 

Islands  of  Mahebourg  Bay,  Mauritius.  Trans.  Bot.  Soc. 
Ediu.,  1895.     Reprinted  with  Additions,  pp.  36,  1896. 

W.     BOTTING    HEMSLEY. 


27 


SELECTION   IN  MAN. 

QUESTIONS  respecting  the  origin  and  development 
of    race-types    have    been    among    the    favourite 
battle-grounds  of  anthropologists  since  anthropology  began 
to  be.      Some  have  held  that  the  countless  varieties  of  type 
in  man  could  be  accounted  for  by  the  simple  admixture  of 
a  very  few  original  types,  of  three  for  example,  a  white,  a 
black  and  a  yellow  one,  others  that  nothing  was  needed  to 
produce   the  widest  extremes  of  variation  save  the  direct 
influence    of   what    the     French    call     "media"    and    the 
Americans  environment.     With  the  development  and    in- 
creasing prevalence  of  evolutionary  theories,  the  questions 
were  looked  upon  from  a  somewhat  different  point  of  view. 
The  same  two  parties,  however,  continued  to  exist,  the  one 
assigning  supreme  importance  to  innate  variability  controlled 
by    natural  selection,     the  other    to    the  same    variability 
controlled  by  environment.      In  process  of  time  it   became 
obvious  that  there  might   be  other  selective   agencies  than 
those  commonly  understood  by  the  term  natural  ;  and  Alfred 
Wallace    himself  pointed    out  that    natural    selection   must 
have  been  potent  in  its  working  on  man  in  the  early  stages 
of  civilisation,   but   that  in  later  stages  it  ceased  to  be  so, 
while  other  agencies  came  into  play. 

Questions  dependent  on,  or  arising  out  of  those  already 

mentioned  are  innumerable,  and  in  some   instances  at  least 

are  of  obvious  and   immediate   practical   importance.      For 

example :    Which    are    the    types    of  man    that    are   most 

suitable  for  colonisation  or  acclimatisation  in  different  parts 

of   the   world  ?    and    are    they    recognisable    by    colour  or 

form  of  head,  by  kephalic  or  nasal  index,  by  stature  or  any 

other  visible  character?     What  is  the  connection  or  relation, 

if  any,  between  complexion  and  liability  to  malarial  fever, 

to    syphilis,    to   cancer  or   leprosy?     Are  the   more  fertile 

types  or  strains  of  mankind  to  be  known  by  outward  signs  ? 

Are  new  types  of  man  likely  to  be  developed  more  suitable 

than  those  now  prevailing  to  the  altering  conditions  of  civic 

and  industrial  life,  and  if  so,  through  what  agencies  ? 


SELECTION  IN  MAN.  385 

Let  us  begin  with  the  subject  of  complexion  or  colour, 
because  it  is  one  of  the  most  conspicuous  differential  char- 
acteristics of  man.  The  xanthochroic  type  of  Huxley,  the 
blond,  at  present  so  dominant  and  aggressive,  occupying, 
in  conjunction  it  is  true  with  the  melanochroic  (or  dark 
white),  more  and  more  of  those  parts  of  the  earth,  such  as 
North  America,  Australia  and  South  Africa,  which  have 
hitherto  been  the  patrimony  of  the  brown  or  the  black  man 
— is  there  reason  to  expect  that  it  will  hold  its  own  outside 
of  its  original  habitat,  or  even  there  ? 

The  historical  evidence  is  on  the  surface  at  least  un- 
favourable. If  we  take  the  words  used  in  their  most  natural 
sense,  we  must  allow  that  the  Greeks  and  Romans  de- 
scribed not  only  the  Germans  but  the  Gauls  and  Thracians 
as  blond.  And  they  did  not  mean  simply  that  the  blond 
complexion  was  pretty  common  among  these  northern 
people  ;  that  could  hardly  have  struck  them  as  very  re- 
markable ;  for  if  they  had  not  had  among  themselves  pretty 
frequent  examples  of  it,  their  descriptions  of  the  four  tem- 
peraments could  hardly  be  explained.1  Literary  portraits, 
and  personal  names  such  as  Flavius,  Rufus,  Ahenobarbus, 
leave  no  doubt  that  there  was  considerable  variety  of  com- 
plexion among  the  Romans  of  the  republican  period,  though 
dark  hues  may  have  prevailed  ;  and  it  does  not  appear  that 
the  continual  influx  of  northern  blood  has  been  able  to  do 
much,  if  any,  more  than  to  maintain  the  status  in  that 
respect.  The  Greeks  ascribed  yellow  locks  to  Achilles  and 
Menelaus  and  other  chieftains  of  the  heroic  age  ;  but  in  the 
imperial  age  the  Egyptian  limners  represented  Greek 
ladies  with  black  hair  and  eyes.  The  ballads  of  Mount 
Rhodope,  believed  to  be  of  extreme  antiquity,  and  refer- 
ring to  Philip,  Alexander,  and  even  Orpheus,  ascribe  yellow 
hair  to  their  heroes  ;  but  the  Pomaks  of  the  Rhodope  are 
not  now  a  blond  race.2  Another  argument  may  be  de- 
rived from  the  ancient  Egyptian  wall-paintings.      Not  only 

1  Among  the  marks  of  the  sanguine  and  lymphatic  temperaments  light 
hair  is  generally  mentioned,  while  black  hair  belonged  to  the  choleric  and 
the  melancholic.  2  Fligier. 


386  SCIENCE  PROGRESS. 

the  Lebo  or  Tahennu  and  the  Amorites  (both  probably 
enough  of  North- European  origin,  though  domiciled  in 
Lybia  and  Canaan),  but  some  of  the  Arabian  Shashi  are 
represented  as  of  xanthous  complexion.  Yet  now-a-days 
we  hear  nothing  of  blonds  in  the  Arabian  or  Egyptian 
populations,  except  where  recent  admixture  of  blood  may 
be  suspected.  Again,  Flinders  Petrie's  recent  discovery 
of  the  remains  of  a  tall,  brown-haired,  and  apparently 
"Aryan"  population  in  Middle  Egypt,1  that  seems  to  have 
completely  and  speedily  disappeared,  reminds  us  of  the 
generally  accepted  statement  that  the  Mamelukes  have  no 
representatives  in  the  Egyptian  population  at  the  present 
day.  On  the  other  hand  the  alleged  blond  coloration  of 
the  Guanches  in  the  Canary  Islands,  and  the  known  fre- 
quency of  that  complexion  in  the  people  of  the  Riff,  and  in 
the  Kabyles  of  some  mountainous  regions  further  east, 
make  it  probable  that  the  type  of  the  Tahennu  still  exists 
where  climatic  conditions  are  not  unfavourable  to  it.  And 
after  all,  these  Tahennu  may  have  been  only  a  blond 
military  aristocracy  ruling  a  melanochroic  plebs  ;  had  it 
been  otherwise,  allowing  that  they  had  come  from  the 
north,  why  did  they  not  perpetuate  an  Aryan  language  in 
North  Africa  ? 

Again,  the  large  xanthous  element  in  the  Jews  has  been 
accounted  for  by  the  existence  of  an  ancient  Amorite  cross  ; 
and  on  the  whole  this  appears  to  me  the  most  probable 
explanation.  We  can  hardly  doubt  its  antiquity  in  any 
case,  since  it  is  present  in  every  section  of  the  Jewish 
people,  and  is  very  distinct  among  the  Sephardim  of  the 
Levant,  though  perhaps  larger  in  proportion  among  the 
Ashkenazim,2  whose  Gentile  neighbours  are  so  largely 
blond.  In  some  parts  of  the  Levant,  indeed,  among  the 
dark  Turks  and  Armenians,  a  red  beard  raises  a  suspicion 
of  Hebrew  ancestry. 

On    the  whole  this   kind  of  evidence,   of  which   much 

1  "  Indications   of    the   earliest     English    occupation    of  Egypt,"  as 
De  Lapouge  pointedly  remarked. 

2  Jacobs  and  Spielmann,  Anthrop.  Trans.     Beddoe,  Ethn.  Trans. 


SELECTION  IN  MAN.  387 

more  might  be  adduced,  leads  me  to  think  that  though 
selective  agencies  in  the  warm  Mediterranean  regions  are 
on  the  whole  adverse  to  the  perpetuation  of  the  blond 
type,  they  are  not  so  everywhere  or  in  very  high  degree. 

Most  of  what  evidence  we  have  from  northern  countries 
makes  one  doubt  whether  any  change  has  occurred  except 
through  immigration  from  melanochroic  areas,  and  con- 
sequent admixture  of  blood.  The  Icelandic  Sagas  show 
that  the  Norsemen  in  the  tenth  century  wTere  as  diverse  in 
colour  of  hair  as  they  are  now  ;  in  fact  the  number  of 
persons  qualified  as  "black"  would  be  a  little  surprising,  if 
one  did  not  allow  for  the  probable  inclusion  of  some  whose 
hair  was  really  only  dark  brown.  The  carefulness  of  the 
descriptions  is  vouched  for  by  coincidences  ;  thus,  chiefs 
with  a  mixture  of  Irish  blood,  such  as  Skarphedinn  and 
Kjartan,  betray  it  by  some  Irish  feature.  The  eyes  are 
seldom  mentioned  ;  but  Egil  Skallagrimson,  a  pure  Nor- 
wegian, had  black  eyes. 

Similarly  the  old  Irish  poems  and  legends  testify  to  the 
occurrence  of  the  same  varieties  of  complexion  that  now 
exist,  and  particularly  to  that  of  the  very  Irish  combination 
of  blue  eyes  and  black  hair,  which  is  ascribed  among  others 
to  the  famous  Diarmaid  O'Duibhne,  the  semi-mythical 
ancestor  of  the  Campbells. 

Nevertheless  I  hold  to  the  opinion,  though  only  as  an 
opinion,  not  as  a  firm  belief,  that  the  modern  Norsemen 
are,  if  anything,  more  generally  blond  than  their  ancestors, 
and  the  modern  Irishmen  less  so.  If  Scandinavia  was,  as 
now-a-days  many  think,  the  officina  or  breeding-ground  of 
the  blond  long-headed  type,  may  not  the  same  agencies 
which  worked  in  that  direction  after  the  close  of  the  last 
glacial  period  be  still  operating  there  now,  though  it  may 
be  less  powerfully  ?  As  for  the  Irish,  it  is  certainly  curious 
that  no  early  English  writer,  so  far  as  I  am  aware,  makes 
mention  of  their  dark  hair.  As  I  have  said  elsewhere, 
Giraldus  tells  us  that  the  Welsh  were  of  swarthy  com- 
plexion, but  he  says  nothing  about  the  colour  of  the  Irish 
(though  he  had  much  to  do  with  them),  except  that  inci- 
dentally   and    casually    he     says    something    about    "  long 


388  SCIENCE  PROGRESS. 

yellow  hair,  like  the  Irish".  The  Irish  colony  about  Dinas 
Mawddwy,  in  Merioneth,  were  called  "the  red  men  of 
Mawddwy".  It  is  probable  that  the  ruling  tribes  of 
Ireland  had  much  more  of  the  blond  element  than  the 
servile  ones  ; 1  and  that  the  former  were  exhausted  by  the 
long  wars  with  the  English,  by  the  military  emigrations  to 
France  and  Spain,  and  perhaps  the  earlier  emigrations  to 
America.  Dr.  Morton,  the  first  great  American  anthropo- 
logist, in  describing  the  Irish  as  he  saw  them,  said  "eyes 
and  hair  light ".  But  there  is  no  doubt  that,  speaking 
broadly,  there  is  more  dark  hair  in  Ireland  than  in  Eng- 
land or  Scotland,  though  there  are  more  dark  eyes  in 
England.  The  climate  of  Ireland,  cloudy,  moist  and 
temperate,  should  favour  the  depigmentation  of  the  eye  by 
natural  selection,  and  I  have  pointed  out  that  the  English 
colonists  of  Ireland  by  mixing  their  blood  with  that  of  the 
natives  have  changed  their  own  type  more  in  the  direction 
of  lightness  of  eye  than  of  darkness  of  hair. 

Mr.  Galton  has  pointed  out  how  rapidly  a  community 
in  which  the  age  of  marriage  is  late  would,  under  like 
circumstances,  be  crowded  out  or  superseded  by  one  in 
which  that  age  is  some  years  earlier.  This  consideration 
is  one  of  several  which  account  for  the  rapid  extinction  of 
upper  class  families  in  these  islands,  while  the  proletariat 
multiplies  with  inconvenient  rapidity  ;  and  as  the  blond 
type  is  more  prevalent  in  the  upper  than  in  the  lower  classes, 
it  also  is  probably  in  process  of  diminution.  If,  however, 
it  can  be  shown  that  the  blond  is  more  subject,  in  this 
country,  to  diseases  of  such  a  nature  as  to  shorten  life,  and 
reduce  the  duration  of  the  period  of  child-bearing  and  child- 
begetting,  this  same  result  would  follow.  Now  there  is  a 
good  deal  of  evidence  as  to  the  greater  liability  of  blonds 
to  certain  classes  of  disease  (in  America  at  least),  in 
Baxter's  great  work  on  the  medical  statistics  of  the  Civil 
War.  There  are  certain  possible  fallacies  which  may 
underlie  Baxter's   figures,  to  some  of  which    De   Candolle 

1  Thus  MacFirbis,  in  a  well-known  passage,  describes  the  Tuatha  De 
Danaan  as  fair,  and  the  Milesians  as  "white  of  skin,  brown  of  hair,"  but 
the  Firbolgs  as  a  servile  race,  and  black-haired. 


SELECTION  IN  MAN.  389 

has  directed  attention  ;  but  if  we  assume  that  the  con- 
clusions which  result  from  them  are  at  all  approximately 
Correct,  it  follows  that  the  blonds  in  America  have  less 
chance  than  the  brunets  of  contributing  their  due  propor- 
tion to  the  next  generation.  Under  these  conditions  the 
blonds  ought  to  diminish  relatively,  and  the  brunets  to 
increase  ;  and  accordingly  we  find  that  of  accepted  soldiers 
there  were  among  the  white  natives  of  the  United  States 
about  (per  cent.) 

66  light  and  34  dark  complexioned,  but 
among  the  English     70        ,,         30  ,, 

Irish  70        „         30 

„  Germans  69        ,,         29  „ 

Thus  the  men  of  American  birth  yielded  a  larger  pro- 
portion of  brunets  than  those  of  any  of  the  nations  that 
had  most  largely  contributed  to  their  ancestry,  which  is 
nearly  equivalent  to  saying  that  the  Americans  are  more 
generally  dark  complexioned  than  their  ancestors  were. 
Gould  (quoted  by  Ripley)  found  that  the  natives  of  the 
eastern  states  were  also  darker  than  those  of  the  west. 
But  whether  this  last  fact  is  occasioned  by  the  parentage 
of  the  western  men  being  more  directly  European,  or 
whether  it  is  connected  with  the  more  migratory  character 
of  the  blond  type,  must  be  left  for  the  present  undeter- 
mined. 

Of  European  evidence  on  the  relation  of  complexion 
and  disease  there  is,  so  far  as  I  am  aware,  no  great  amount. 
My  own  observations  have  shown  that  it  is  a  mistake  to 
suppose,  as  many  do,  that  light-haired  persons  are  in 
England  more  liable  to  phthisis  than  others.  I  have  also 
pointed  out  that  cancer  is  more  common  in  persons  of  dark 
complexion,  and  in  this  I  am  supported  by  the  observations 
of  Dr.  Roger  Williams.  This  last  fact  has,  however,  very 
little  bearing  on  the  subject  in  hand,  for  as  cancerous  disease 
usually  attacks  persons  who  are  beyond  the  child-producing 
age  it  can  have  very  little  effect  on  the  proportions  of  the 
different  complexions  of  the  next  generation. 

As  we  possess  for  France  not  only  elaborate  recruiting 
statistics,  with  numerical  lists  for  the  principal  disqualifying 


390  SCIENCE  PROGRESS. 

diseases,  but  also  Topinard's  departmental  statistics  of 
colour,  and  Collignon's